In the infinite choice of CO2 sensors, how do you pick the most suitable one?
When purchasing/renting a CO2 meter, check whether it is of high quality and suitable for measuring in the space you want to install it. Other things you should pay attention to are: sensor type, measurement error, measuring range, calibration method, LED indicators, LED indication values, model and data logging.
In this article, we will take a closer look at some of these aspects.
NDIR sensor technology
It is advisable to choose a sensor that detects CO2 based on the NDIR principle. NDIR or non-dispersive infrared sensors contain an infrared (IR) lamp that directs waves of light through a tube filled with air towards an optical filter in front of an IR light detector. This detector measures the amount of IR light that passes through the optical filter. The difference between the amount of light radiated by the IR lamp and the amount of IR light received by the detector is measured. In this way the number of CO2 molecules in the air can be calculated.
It is advisable to choose a sensor that detects CO2 based on the NDIR principle. NDIR or non-dispersive infrared sensors contain an infrared (IR) lamp that directs waves of light through a tube filled with air towards an optical filter in front of an IR light detector. This detector measures the amount of IR light that passes through the optical filter. The difference between the amount of light radiated by the IR lamp and the amount of IR light received by the detector is measured. In this way the number of CO2 molecules in the air can be calculated.
The advantage of such NDIR CO2 sensors is their lengthy lifespan, the minimal to zero interference of other gases, low life-cycle cost and a precise and stable long-term operation. This is something Sentera Controls understood very well and therefore developed all its CO2-sensors based on the NDIR principle.
Calibration method
All carbon dioxide sensors need calibration. In case of the NDIR sensors, both the light source and the detector deteriorate over the years, resulting in slightly lower CO2 molecule counts. This is generally known as “drift” or measurement error. Depending on the application, calibration can be accomplished by calibrating the sensor to a known gas or using the automatic baseline calibration (ABC) method.
All carbon dioxide sensors need calibration. In case of the NDIR sensors, both the light source and the detector deteriorate over the years, resulting in slightly lower CO2 molecule counts. This is generally known as “drift” or measurement error. Depending on the application, calibration can be accomplished by calibrating the sensor to a known gas or using the automatic baseline calibration (ABC) method.
ABC calibration was developed to solve the difficulty of calibrating wall-mounted units for measuring occupancy or indoor air quality. Removing these units from the wall in order to calibrate them was expensive, required trained staff and was therefore often ignored.
The theory behind ABC self-calibration is that for IAQ use, at some point each day a room is unoccupied and the CO2 level will drop to outside ambient conditions of 400 ppm. All Sentera CO2-sensors make use of the ABC Logic® calibration method. When enabled, the sensor will typically reach its operational accuracy after 24 hours of continuous operation and will maintain its accuracy, given that it is at least four times in 21 days exposed to a reference level of 400 ppm. Depending on the installation environment, it is recommended to enable or disable this self-calibration technique.
Type of information provided
There are different types of CO2 measuring instruments, depending on how the measurement data is displayed, transmitted and/or archived. Some instruments combine different information options.
There are different types of CO2 measuring instruments, depending on how the measurement data is displayed, transmitted and/or archived. Some instruments combine different information options.
Direct display of the measured value on a screen - has the advantage of allowing easy immediate measurement and direct information to the people in the room.
Data registration - the measured data is sent and archived remotely and can be consulted via an application on a smartphone, computer or website for example. This has the advantage that you can easily visualize and interpret the course of the CO2 values during a certain period and map the influence of certain interventions (e.g. opening extra windows or doors) to improve the rate of air exchange.
Additional visual (green, yellow, red LEDs) and/or audible (alarm) indicators show whether the measured data are still within range or if extra ventilation is needed.
The Sentera product range contains CO2 sensors that require 24 Volt supply voltage and versions that can directly be plugged in into a 230 VAC socket. All the CO2 room sensors have these LED indications visualising one of the measured values. Some of them are additionally equipped with an audible alarm. The sensors can be linked to an external screen showing the measured values. Data logging, remote control and monitoring is also possible by connecting the sensor and associated applications to Senteraweb, our own online HVAC platform. Both Sentera devices and registered non-Sentera devices can be connected to SenteraWeb.
Who is Sentera?
Sentera is one of the leading manufacturers of control solutions for HVAC and ventilation systems. Our mission is to make intelligent HVAC control solutions that are easy to use! We develop, manufacture and promote fan speed controllers, HVAC sensors, HVAC controllers and actuator powered dampers to control airflows and to monitor indoor air quality. Today, the Sentera group counts 8 companies and 150 employees based in 4 different locations. Headquarters and the central warehouse are located in Temse, Belgium. Sentera is a 100 % family owned group of companies. For more information, please contact Sentera!
Why is Internet of Things (IoT) so important?
Over the past few years, IoT has become one of the most important technologies of the 21st century. Today, our planet has more connected devices than it has people. The IoT will transform the way businesses, governments and humans interact with the rest of the connected world. In this hyper connected world, digital systems can record, monitor and adjust each interaction between connected things. The physical world meets the digital world—and they cooperate.
IoT and Sentera
Sentera is known for its high-performance HVAC control solutions that are easy to use. Innovation has always been one of our main strengths. Thanks to IoT technology, we can make our products more intelligent and tailor them even better to meet the requirements of your application. When a technical fault occurs in a ventilation system, the ventilation system itself will send a warning. Thanks to data logging it is possible to view and evaluate the indoor air quality of the past weeks. Is the capacity of the ventilation system sufficient?
SenteraWeb - IoT for the HVAC industry
Via an internet gateway, Sentera product(s) or solutions can be connected to SenteraWeb. This is a software platform that was developed by Sentera and is optimally tailored to our products and solutions. The connected devices send data to SenteraWeb and receive firmware updates or parameter updates. Do you have an HVAC control solution with Sentera sensors and an EBM-Papst EC motor, an Invertek frequency controller or a Grüner damper actuator? Don't worry, these products can also be connected to SenteraWeb.
What is the benefit for the customer?
HVAC control solutions that are connected to SenteraWeb, offer the customer many benefits. Today, following functionalities are available:
Data logging - All values measured by the connected devices are stored in SenteraWeb. This makes it possible, for example, to view the evolution of temperature, humidity or CO2 values over the past few weeks.
Receive alerts - If a threshold value is exceeded, the ventilation system sends you a warning. In case of a defect an alert can be sent.
Remote control - SenteraWeb makes it possible to remotely monitor the status of a connected device or to adjust settings.
Firmware updates - Connected devices can receive a firmware update via SenteraWeb. Additional functionalities can be made available via new firmware. Application specific firmware can be downloaded via SenteraWeb. So the customer does not need to program a 'universal HVAC controller' - just download the firmware for your application and adjust some settings. HVAC distributors can sell standard Sentera products.
Reduce stock - Via a firmware update, several functionalities are available. This allows the HVAC distributor to reduce the number of item codes in stock.
And more to come!
Typical applications
End users can receive an alert when the air filter of their ventilation system is clogged and needs replacement.
Schools, restaurants or sport clubs can receive a warning when the CO2 level exceeds the threshold value. By analyzing the CO2 loggings, it is possible to see if the capacity of the ventilation system is sufficient in different circumstances.
HVAC installers can receive a notification when the fresh air supply drops below the minimum threshold value. They can schedule an intervention before their customer detects a problem.
AHU manufacturers can monitor their installations in the field. Current consumption, air volume flows and other data can be logged. Based on these data, they can further optimize their installations.
The future of HVAC control solutions
Ventilation and good indoor air quality is essential. To assure good indoor air quality, the ventilation system must operate fully autonomously on a continuous basis. The additional possibilities offered by IoT technology can make an important contribution to the reliability of a ventilation system. With the insight provided by advanced analytics comes the power to make control solutions more efficient. In the years to come, SenteraWeb will allow us to further optimize our control solutions and tailor them even better to your needs. Our HVAC control solutions will become more and more intelligent and discreetly create your perfect environment.
As a leading manufacturer of control equipment for ventilation systems, Sentera is proud to present its latest product - the ACT-H-125. With the introduction of this circular motorized control damper, the Sentera product range becomes even more complete and better adapted to the current needs in the HVAC sector.
Round motorized control damper
The Sentera ACT-H-125 is a round motorized control damper for air ducts with a diameter of 125 mm. Because the channels are slid into the damper, no extra air resistance is created thus ensuring optimum efficiency. After mounting, the connection between the damper and the duct must be sealed with aluminum tape to ensure airtightness.
RJ45 socket and a classic terminal block
The ACT-H-125 is equipped with an RJ45 socket and a classic terminal block. You can therefore choose Modbus RTU connection or connection with an analogue control signal. When the damper is connected via Modbus RTU, the data and the 24 VDC power supply are connected by one single cable. If the terminal block is used, 2 cables must be provided: 1 for the 24 VDC power supply and 1 for the analogue signal (0-10 VDC / 0-20 mA / PWM).
Controlled via analogue signal or Modbus RTU
The damper blade position can be controlled by analog signal or via Modbus RTU communication. The minimum and maximum position and many other parameters can also be adjusted in the Modbus registers. The damper blade offers a Class 4 airtightness, while the casing offers a Class D airtightness (EN1751). It can control airflows with a speed between 0 and 10 m/s.
Optimal demand based control of the ventilation system
The ACT-H-125 can be combined with many Sentera sensors. This ensures optimal demand based control of the ventilation system. For example, when using a Sentera CO2 sensor, it will automatically adjust the damper blade position when more or less ventilation is required. A Sentera differential pressure controller that regulates the fan speed then provides an adjusted air flow rate when one or more dampers are opened or closed.
You will find all technical information as well as product photos of the ACT-H-125 on the Sentera website. For more information and prices, please contact one of our employees.
As a leading manufacturer of control solutions for HVAC and ventilation systems, Sentera offers a wide range of products that can be used individually or combined as a complete solution.
CO2 based damper control
Especially for the open house at one of our customers, we built a VAV demo unit in which various Sentera product groups are incorporated to work together as one solution. This solution is based on our new ACT-H-125 valves which are controlled by means of an analog signal from our DCMFF-2R CO2 duct sensors. When the CO2 level increases, the sensor will open the valve to allow more fresh air to be supplied. Several valves, each with their own sensor, can be used in the same installation. To guarantee a constant supply of fresh air (regardless of how many valves are open), the fan is controlled by an electronic EVS fan speed controller, which in turn is controlled by a DPS differential pressure controller. When opening the valve(s), the differential pressure will drop and the differential pressure controller will increase the fan speed via the electronic fan speed controller to guarantee the necessary flow rate.
Differential pressure based fan speed control
Conversely, when closing the valve(s) (when the CO2 level drops) the differential pressure will increase and the DPS differential pressure controller will decrease the fan speed via the electronic EVS fan speed controller to bring the flow back down to the required level.
All parameters of the Sentera products used can be adjusted according to the application or requirements via the Sentera Modbus converter and the free 3SModbus software.
To explain the complete operation of this installation step by step, we have made a detailed video which you can watch here. To obtain an increase in the CO2 level into the ventilation duct in order to demonstrate the operation of the installation, CO2 is added by means of an aerosol.
The following Sentera products were joined into one solution in this installation:
- ACT-H-125 round motorized control valve: round motorized control valve for 125mm diameter air ducts. The damper blade position can be set via a 0-10 V signal or via Modbus RTU communication. The minimum and maximum position and many other parameters can also be adjusted in the Modbus registers.
- DCMFF-2R intelligent CO2 duct sensor: air duct sensor that measures CO2, temperature and relative humidity. It combines these 3 measured values in one intelligent output to which you can directly connect the EC fan or control valve.
- DPSPF-1K0-2 differential pressure controller 1 kPa with display: high resolution differential pressure and airflow controller with display, 0-1000 Pa range, integrated PI control and K-factor, analogue / modulating output 0-10 VDC / 0-20 mA / PWM, Modbus RTU communication.
- EVS-1-15-DM 1,5 A electronic fan speed controller with analogue input and Modbus: the EVS controls the speed of single-phase voltage-controllable motors. The technology used is phase angle control (Triac technology). They have Modbus RTU communication and an input to remotely start/stop the motor. The minimum and maximum speeds are internally adjustable via a trimmer. The output voltage to the motor is within the range between the set minimum output voltage (30-70% of the supply voltage) and the supply voltage and can be controlled via the analogue input (0-10 VDC / 0-20 mA) or via Modbus RTU.
- RDPU-HMU HVAC controller: central HVAC controller with built-in touch screen. Depending on the firmware that is loaded in the device, there are different applications. In this case it is the HMU Home Monitoring Software. This allows you to monitor the air quality in every room of your building. This solution is extremely suitable for a private home, but also for a school or (public) building.
- SIGWM internet gateway: An internet gateway for Sentera products. It connects to the internet via the local Wi-Fi network. This makes setting up your Sentera network easier. It also offers the possibility to access your installation remotely. Connect and monitor or control your compatible HVAC products remotely. You can log data and receive alarms. Define different users and create your personal dashboard.
- SEPS8-24-40 switching power supply: supply voltage: 85-264 VAC / 50-60 Hz, output voltage: 24 VDC / 40 W / 1.67 A, IP65, connections via spring clamp connectors or via RJ45 connectors. Power over Modbus (PoM) compatible. Protected against overvoltage and overcurrent.
- MDB-M-6 Modbus RTU distribution box with 6 channels: both the 24 VDC supply voltage and the Modbus RTU communication are distributed over the 6 RJ45 connectors. MDB-M/6 is compatible with Sentera sensors, sensor controllers, HVAC controllers and speed controllers with Modbus RTU communication.
All products work together as a complete VAV solution that can be monitored and set up remotely via Senteraweb. If you have any questions about this setup after watching this video, or if you would like more information regarding other solutions, do not hesitate to contact one of our employees.
Did you know that Sentera offers numerous solutions for ventilation systems in the catering industry?
Sentera transformer fan speed controllers are used by our customers in professional kitchens all over the world. They are intended for stepped speed control of the electric motors in (a.o.) cooker hoods. They use autotransformer technology to reduce the motor voltage - and fan speed - in steps. Thanks to this technology, they generate a motor voltage with a perfect sinusoidal shape. This results in exceptionally quiet motor operation and extended service life. Transformer fan speed controllers are cost efficient and have proven to be very reliable and robust. They can also be used in circumstances with unstable power supply. These type of fan speed controllers are easy to install and don’t require any configuration. Some transformer fan speed controllers have an integrated rotary switch to manually adjust the fan speed, while other variants can be controlled remotely via Modbus RTU or via an analogue control signal. Some even have an emergency button to activate smoke extraction.
Under pressure areas
In situations where under pressure is required, to keep odours out of certain areas, the Sentera differential pressure controllers can be used to control the ventilation system. These HVAC controllers are used to control differential pressure or air volume flow. Air velocity control is also possible in combination with a pitot tube. Typically these products are used to guarantee a constant volume flow under fluctuating demands or to maintain a difference in air pressure between two rooms, keeping unwanted odours out of certain areas.
Filter guard
In an efficient and well maintained ventilation system, a filter guard is indispensable. Sentera differential pressure sensors can measure differential pressure, air volume flow or air velocity. A typical application is to monitor differential pressure over an air filter and generate an alert in case the filter is polluted. The measured value is transmitted via an analogue output and via a Modbus RTU register. All settings can be adjusted via Modbus RTU.
So, when enjoying your next lunch or dinner, remember that Sentera is never far away. Have a nice holiday!
Innovation is our motivation!
Since 1997 Sentera has been a leading manufacturer of innovative control equipment for HVAC systems. Innovation is our motivation! In addition to the development of sensors and fan speed controllers, we also offer numerous network solutions for ventilation systems. The 'Internet of Sentera' is our latest development and allows you to monitor and configure your ventilation system via the internet. For more information about our products and solutions, you can always contact one of our employees.
The importance of indoor air quality
In these modern times we spend more and more time indoors. Some studies indicate that we spend an average of 90% of our time indoors! Homes and buildings are better insulated to save energy. Better insulation and airtightness of homes creates the need to ventilate them better. After all, ventilation is necessary to keep indoor air quality under control. The indoor air we breathe is not only important for the comfort and concentration of residents. It also has a direct impact on our health. Certainly in the long term. Typical complaints caused by long exposure to poor air quality range from headaches, irritation of the eyes, nose and throat to serious conditions such as respiratory disease, heart disease and cancer. The importance of monitoring and optimizing indoor air quality should therefore not be underestimated. A well maintained ventilation system removes harmful substances from the indoor air and replaces them with filtered, fresh outdoor air.
Excessive ventilation has no negative impact on indoor air quality. The disadvantage of too much ventilation is unnecessary energy consumption. This energy consumption consists on the one hand of electrical energy and on the other hand of thermal energy. The higher the fan speed, the more electrical energy it consumes. Most fans have a quadratic torque curve. This means that even a small reduction in fan speed can yield significant energy savings.
In addition, there is also the thermal energy. When cold outside air is brought into a house and the warm, used air is removed from the house, a loss of heat (thermal energy) occurs. Thanks to modern ventilation systems with high-efficient heat exchangers, these losses are negligible. Further optimization is possible by controlling the air volume flows (controlling fan speed). HVAC sensors monitor indoor air quality. Based on these measurements, fan speed can be optimised. In this way, the supply of fresh air can be controlled demand based and good indoor air quality can be combined with energy efficiency. There are many different options for measuring indoor air quality. The nature of the indoor space often determines the type of sensor that is required to keep the air quality optimal.
Temperature and humidity are the basic parameters
Temperature and humidity have a direct influence on our feeling of comfort. Neither a cold, damp environment nor a dry, warm room make us feel comfortable. Depending on our activity, we will feel most comfortable in a room with a temperature between 20 and 25 °C and a relative humidity between 35 and 60 %. Through our daily activities such as cooking, showering, drying the laundry, etc., we bring a lot of moisture into the home. When it is well insulated and airtight, it is difficult for this moisture to escape. Too much moisture in a building is not only a problem for our sense of comfort. It is harmful to the structure of the building and increases the risk of mould formation. Mould formation is detrimental to the health of residents. Inhalation of mould spores increases the risk of the above-mentioned conditions, especially in the long term.
Relative humidity is the ratio of the amount of water vapour in the air to the maximum amount of water vapour that can be present in the air. This maximum value is determined by the temperature. Relative humidity is expressed in %. The warmer the air, the more water vapour the air can absorb. When warm (indoor) air comes into contact with a cold surface – for example a window – condensation occurs. The temperature at which condensation occurs is the dew point temperature or dew point (expressed in °C). A ventilation system must therefore ensure that the relative humidity remains within comfortable limits. Typically this is between 35 and 60%. In addition, care must be taken that the indoor temperature is always higher than the dew point. When the indoor temperature is lower than the dew point, condensation will occur with the risk of mould formation.
Temperature, relative humidity and dew point are the most essential parameters for the comfort of the residents. These parameters are usually taken into account when controlling a ventilation system. For that reason, most professional HVAC sensors can measure these parameters. These basic HVAC sensors prove their usefulness, especially in humid areas such as bathrooms and kitchens.
CO2 as an indicator of indoor human activity
Good ventilation not only keeps the humidity in balance, it also prevents harmful substances and gases from accumulating in the indoor air. One of those gases is CO2 or carbon dioxide. CO2 is not harmful to humans in normal concentrations. It is even one of the 5 main components of our atmosphere, after nitrogen, oxygen, water vapour and argon. Plants cannot grow without CO2. CO2 is less harmless at higher concentrations. When the concentration of CO2 in indoor air becomes too high, complaints of drowsiness, loss of concentration and subsequently headaches occur.
Without a ventilation system, CO2 concentrations can increase very quickly in a closed space. The more people are present and the more physical activity there is, the faster the CO2 concentration will rise. In our body, food containing carbon is 'burned' and converted into energy. This metabolic combustion process releases CO2. We then exhale this carbon dioxide. Measuring the CO2 concentration in the indoor air therefore provides relevant information about the occupancy rate of a room and about the need for extra supply of fresh air.
The CO2 concentration in an enclosed space also gives an indication of the risk of the amount of aerosols in the air. Aerosols can spread viruses. They are miniscule droplets that are released when coughing, sneezing or talking. When other people inhale these droplets or get them into their mouth, nose or eyes through their hands, they can become infected with the virus. To make the residents feel comfortable and to prevent drowsiness and loss of concentration, it is recommended to keep the CO2 level below 800 ppm through a sufficient supply of fresh air.
CO2 sensors give a good idea of the occupancy rate of a room because the CO2 concentration correlates with human activity. This type of sensors is therefore mainly used in rooms with strongly fluctuating occupancy rates. The higher the detected CO2 concentration, the higher the human activity and the more ventilation is required. Not only the metabolism of humans and animals is responsible for the production of CO2. In addition to human activity, there are many other sources of CO2 production. CO2 is also created during the (complete) combustion of fossil fuels. The CO2 concentration in the outside air therefore depends on the region. It will be higher in an urban environment than in a rural environment. A typical CO2 concentration in outdoor air is about 450 ppm.
How can the CO2 level remain more or less constant when people and animals have been walking around for centuries that produce CO2? Nature itself ensures that CO2 is removed from the atmosphere. Trees and plants convert CO2 into carbon and oxygen during the photosynthesis process. The carbon is used by plants to grow. Trees and plants themselves consist largely of carbon. The oxygen is released by the trees and plants into the atmosphere. Oceans also absorb CO2 from the air. The carbon dioxide is first absorbed in the upper layers of the ocean and then sinks to greater depths, where krill, plankton and seaweed convert it back into carbon and oxygen. However, these processes take a long time. The combination of global population growth and ever-increasing industrialization disrupts this natural balance. Human activity emits much more CO2 than the maximum absorption capacity of nature. The extra CO2 molecules that linger in the atmosphere absorb infrared radiation – also known as heat radiation – and send some of it back to Earth. As a result, the earth is slowly warming up more and more.
VOC as a measure of indoor air quality
VOC or Volatile Organic Compounds is a collective name for a group of chemicals that can be present in a residential environment. They are volatile or rapidly evaporating products containing one or more carbon atoms (organic substances). Typical examples are benzene, ethylene glycol, formaldehyde, methylene chloride, tetrachloroethylene, toluene, xylene and butadiene. These chemicals can be found in household environments in cleaning products, perfumes, solvents in paints and propellant for hair spray cans. VOCs are also found in fragrance fresheners, building materials and cigarette smoke. The typical smell of new furniture or a new car can give a pleasant feeling. In reality it is a mixture of volatile organic compounds. In the open air, VOC concentrations are normally quite low. On busy roads and in cities, a higher VOC concentration can be measured, usually as a result of exhaust gases. The effect and harmfulness of these substances is very diverse.
Sometimes you can smell the presence of high concentrations of VOC (e.g. smell of paint), but harmful concentrations can also be present without you noticing. The impact on the health of residents depends on the nature of the VOC, the amount of VOC inhaled and the duration of exposure. Short exposure to a high VOC concentration, such as during painting or when using cleaning agents, can cause dizziness, nausea, concentration problems and irritation of the eyes and respiratory tract. These effects are temporary. OPS or Organo Psycho Syndrome is a known consequence of prolonged or repeated exposure to high VOC concentrations among professional painters. This manifests itself in all kinds of mental problems and memory problems. The damage caused in this way is permanent. At typical VOC concentrations in a residential environment, the effects are less obvious. Often there are no complaints in the short term and you do not smell the VOCs.
VOCs are volatile, so the concentration will decrease over time. This period depends on the source and the VOC concentration. New construction and renovation work, but also a carpet or a new sofa usually temporarily cause higher VOC concentrations in the indoor air. Extra ventilation is then recommended during the first months. The use of VOCs indoors should be limited as much as possible, given their negative impact on indoor air quality. At higher VOC concentrations, extra ventilation is the solution. In principle, VOC sensors can be used in all rooms. Especially in storage areas for detergents and in bathrooms, a VOC sensor is the obvious choice.
Detect toxic gases via CO and NO2 sensors
Carbon monoxide (CO) is a colourless, odourless and tasteless gas. It is an extremely dangerous gas. CO is created when fossil fuels (coal, gas, fuel oil, wood, pellets, petroleum, etc.) are burned incompletely or poorly. CO can therefore only be formed where there are flames and in the room where the heating appliance is located. CO is slightly lighter than air, but the difference is so small that in practice CO usually mixes completely with normal air in enclosed spaces. It is therefore sometimes called the silent killer. The World Health Organization (WHO) applies a maximum limit of 6 ppm for continuous exposure. Increasing to a maximum of 26 ppm with an exposure of 1 hour per day.
In humans, haemoglobin, the dye in red blood cells, carries oxygen from the lungs to the cells. The affinity of CO for haemoglobin is 210 to 260 times higher than that of oxygen. Even in the presence of low concentrations, CO will attach to haemoglobin instead of oxygen. This disrupts the transport of oxygen to the cells and causes an oxygen deficiency. An exposure to low CO concentrations will initially be recognizable as symptoms of nausea, dizziness and headache. The victim feels weak and is easily short of breath with moderate exertion. Over time, the victim will lose consciousness and - if no help arrives - die. It goes without saying that toxic gases such as carbon monoxide must be removed from the building as quickly as possible. As soon as this gas is detected, sufficient fresh air must be supplied.
The same applies to other toxic gases such as nitrogen oxides (NOx). NOx is the collective name for NO and NO2. NOx is created during combustion processes at high temperatures and can be found in exhaust gases from cars with a combustion engine. In addition, NO2 - just like CO - is also created during incomplete combustion processes. NO2 is also a poisonous gas that is harmful to health. People with lung complaints and asthma suffer from it in particular.
CO and NO2 sensors are therefore mainly used in parking garages or in technical areas where heating appliances are installed. As soon as toxic gases are detected, sufficient ventilation must be provided to restore safe indoor air quality as quickly as possible.
The advantage of demand-controlled ventilation
Each room in a building has a specific purpose. Therefore, a room is rarely used continuously usually not always with the same intensity. The bathroom for example is typically used in the morning and evening. Bedrooms during the night. Each room in a building has its own specific usage and occupancy pattern. A ventilation system is usually calculated with an overcapacity so that it can supply sufficient fresh air during peak times. Typically, these peak moments only represent a limited part of the total cycle. Most of the time, the ventilation system can operate at low speed. By applying the right sensors in each room and controlling the ventilation system based on these measurements, the indoor air quality can be optimized and at the same time significant energy savings can be achieved. An additional advantage is that a ventilation system produces less noise when it works at low speed.
Modern ventilation systems for homes or (commercial) buildings often use a central ventilation group or air handling unit (AHU) that may or may not be equipped with a heat recovery system. In a home, this central ventilation system is usually located in the attic, while in a (commercial) building it is usually installed outside on the roof or somewhere next to the building. Attached to this central ventilation system is a network of air ducts, each of which has a ventilation grid at the end. In the past, these grids were often manually adjusted per room to obtain the desired flow rate. Nowadays, there are electrically operated grids. Even better is to provide a fully automatic VAV or CAV control valve at the end of the duct, right before the grid.
Constant pressure control
Whether we control with a manually adjustable grid or with an automated VAV / CAV damper, by controlling the dampers per room or per zone, we are obviously not there yet. If the central ventilation system, equipped with one or more fans, does not adjust its speed according to the total demand of fresh air within the network, then controlling the dampers would simply result in more draft and noise entering the room through the grids. It is therefore necessary to install a differential pressure controller in the main duct, just before the central ventilation unit. This controller guarantees that the speed of the fans gets adjusted in relation to the total demand. Only thanks to this constant pressure control will the position of the dampers actually result in the desired air volume for each individual room.
Some central ventilation systems have a built-in differential pressure controller, while others have an analog or digital input to which a control signal from an external differential pressure controller can be sent. Sentera offers a wide range of differential pressure controllers. Most of them can be equipped with a Pitot tube, which allows air velocity measurement. This is even more convenient and often more accurate than differential pressure measurement.
VAV dampers for variable air volume
For reasons of energy efficiency, we prefer demand based ventilation of the rooms in our home or in our building. This means that we will no longer work with manually adjustable grids, but will use sensors to measure the air quality in a room and ventilate just enough to maintain good air quality. After all, ventilating more than necessary would often involve loss of heat (in winter, that is), and that is obviously irresponsible, both for environmental and economic reasons. The room sensor, duct sensor or sensor built into the control damper will open or close the VAV-damper position proportionally to the measured air quality. The worse the air quality, the further the valve opens and vice versa. This creates a variable air volume (VAV), related to the measured air quality.
CAV dampers for constant air volume
Unlike a VAV damper that provides a variable air volume according to the air quality, a CAV damper ensures that a room, or a zone receives a predetermined volume of fresh air. A constant air volume (CAV) is often used because it is mandatory, or because it is difficult to measure the air quality in a particular space and ventilate demand-based as is the case with a VAV damper. Every time changes happen in other rooms connected to the same central ventilation group, the CAV damper is going to notice a pressure difference and adjust its valve position to maintain the desired constant air volume setpoint for this particular room.
Can we combine VAV and CAV within one ventilation system?
Yes, it is possible to combine both systems. For example, a demand-based VAV control could be used for landscape offices and meeting rooms and a CAV control for production rooms or workshops. After all, constant pressure control takes into account the sum, the total demand of fresh air for the entire building. Regardless of whether it is VAV or CAV.
What do we need to watch out for?
Minimum flow rate
If duct sensors or sensors built directly into the control damper are used, it is necessary to ensure minimum air circulation to allow the sensors to measure the room air quality. Because if the air from the room does not reach the sensors, obviously no correct measurement is possible.
VAV and CAV consecutively
As mentioned above, it is ok to combine VAV and CAV in parallel. I.e. that some rooms are controlled by CAV and others by VAV. In some cases however, systems are designed where upstreams in the duct system CAV dampers are used and further down the ducts VAV dampers are used to provide demand based air volume to the different rooms. As you might expect, this creates additional challenges in the balancing process. Partly because CAV dampers need a certain minimum volume (pre-pressure) to keep their air volume constant. If the VAV dampers that are located behind a CAV damper no longer demand enough flow, the CAV damper will have difficulty maintaining its set flow rate.
SenteraWeb cloud services make balancing easier
Needless to say, designing and controlling a central ventilation system can be quite complicated. The fact that Sentera VAV or CAV control valves are equipped with Modbus communication and can therefore be remotely monitored and adjusted can result in enormous time savings. Savings are also made in travel costs and working hours. Even if the customer subsequently wants to make parameter changes or expand the system, large costs can be saved thanks to SenteraWeb cloud services.
Sentera CAV valves
With the ACDPH-125, Sentera has a 125 mm round CAV control valve in its range. Modbus RTU allows it to be remotely controlled and read out or it can be included in your HVAC network. 160 and 200 mm CAV valves are currently under development.
Sentera VAV valves
With the ACT-H-125 and ACT-H-160, Sentera currently has 2 motorised circular VAV valves in the range while a 200 mm version is under development. These ACT-H valves can be controlled via Modbus RTU or via a 0-10 VDC control signal. This makes them compatible not only with Sentera sensors, but also with third-party sensors. Sentera VAV valves with built-in CO2, TVOC, CO, temperature and relative humidity sensors are currently under development.
What is a cleanroom?
Cleanrooms are specialized environments designed to maintain extremely low levels of particulate and microbial contamination. They are widely used in industries such as pharmaceuticals, biotechnology, electronics, and aerospace, where even the tiniest contaminants can have a significant impact on product quality, safety, and performance.
The primary objective of a cleanroom is to control the concentration of airborne particles, usually measured in terms of particles per cubic meter. The International Organization for Standardization (ISO) has established standards such as ISO 14644-1 to classify cleanrooms based on the maximum allowable particle concentration.
Cleanrooms achieve their high levels of cleanliness through a combination of engineering controls, strict protocols, and specialized equipment.
The following key components are typically found in a cleanroom:
1. Air Filtration Systems: Cleanrooms are equipped with advanced HVAC systems that use a combination of filters to remove particles from the air. High-efficiency particulate air (HEPA) filters are commonly employed to capture particles as small as 0.3 micrometers.
2. Positive Pressure: Cleanrooms are maintained at a higher pressure compared to surrounding areas, which prevents contaminated air from entering. This is achieved by ensuring that the supply air from the HVAC system exceeds the exhaust air.
3. Controlled Airflow: Cleanrooms are designed to have a controlled airflow pattern, typically a unidirectional or laminar flow. Unidirectional flow moves air in a single direction, while laminar flow moves air in parallel, minimizing the chance of particles settling on surfaces.
4. Cleanroom Garments: Personnel working in cleanrooms are required to wear specialized garments, including cleanroom suits, gloves, masks, and shoe covers. These garments prevent the shedding of particles and microbes from their bodies into the cleanroom environment.
5. Cleaning and Disinfection: Regular cleaning and disinfection protocols are followed to maintain the cleanliness of surfaces, equipment, and tools within the cleanroom. Specific cleaning agents and procedures are employed to minimize the introduction of contaminants.
Cleanrooms are classified into different ISO classes, ranging from ISO Class 1 (the cleanest) to ISO Class 9 (relatively less clean). The classification depends on the maximum allowable particle concentration per cubic meter of air.
In addition to particle control, cleanrooms also address other factors like temperature, humidity, electrostatic discharge, and noise levels, which can affect the quality and integrity of the products being manufactured or researched within the cleanroom.
Overall, cleanrooms are critical in industries that require stringent environmental control to ensure product quality, safety, and compliance with regulatory standards. Their design, operation, and maintenance are carefully executed to provide a controlled environment that minimizes the presence of contaminants, making them indispensable in various cutting-edge fields of science and technology.
How can Sentera help to keep these rooms clean?
1. Our latest new development is an air filter monitoring device. With our FIM you can monitor one or 2 filters and receive a warning via email or sms to inform you that the filters need to be cleaned and/or replaced. Via the local Wi-Fi network or a LAN-cable – depending on which version you choose – you can connect the device to SenteraWeb. Via SenteraWeb you can monitor the values, change parameters, log data and schedule ahead the maintenance or replacement of the air filter(s).
2. To control the airflow and positive pressure in the cleanroom you can rely on our differential pressure sensors and differential pressure controllers. The sensors will transmit the measured value (pressure or air flow) proportionally via the analogue output. The controllers can be used to ensure a constant airflow under changing conditions. The output signal can be used to directly control an EC fan or motorised damper or to control an AC fan via a speed controller or frequency inverter. The output is again based on the measured differential pressure, airflow or air velocity. All settings can be adjusted via Modbus RTU. The sensors and controllers are available with or without small display.
For further information, do not hesitate to contact us.
Cleanrooms are specialized environments designed to maintain extremely low levels of particulate and microbial contamination. They are widely used in industries such as pharmaceuticals, biotechnology, electronics, and aerospace, where even the tiniest contaminants can have a significant impact on product quality, safety, and performance.
The primary objective of a cleanroom is to control the concentration of airborne particles, usually measured in terms of particles per cubic meter. The International Organization for Standardization (ISO) has established standards such as ISO 14644-1 to classify cleanrooms based on the maximum allowable particle concentration.
Cleanrooms achieve their high levels of cleanliness through a combination of engineering controls, strict protocols, and specialized equipment.
The following key components are typically found in a cleanroom:
1. Air Filtration Systems: Cleanrooms are equipped with advanced HVAC systems that use a combination of filters to remove particles from the air. High-efficiency particulate air (HEPA) filters are commonly employed to capture particles as small as 0.3 micrometers.
2. Positive Pressure: Cleanrooms are maintained at a higher pressure compared to surrounding areas, which prevents contaminated air from entering. This is achieved by ensuring that the supply air from the HVAC system exceeds the exhaust air.
3. Controlled Airflow: Cleanrooms are designed to have a controlled airflow pattern, typically a unidirectional or laminar flow. Unidirectional flow moves air in a single direction, while laminar flow moves air in parallel, minimizing the chance of particles settling on surfaces.
4. Cleanroom Garments: Personnel working in cleanrooms are required to wear specialized garments, including cleanroom suits, gloves, masks, and shoe covers. These garments prevent the shedding of particles and microbes from their bodies into the cleanroom environment.
5. Cleaning and Disinfection: Regular cleaning and disinfection protocols are followed to maintain the cleanliness of surfaces, equipment, and tools within the cleanroom. Specific cleaning agents and procedures are employed to minimize the introduction of contaminants.
Cleanrooms are classified into different ISO classes, ranging from ISO Class 1 (the cleanest) to ISO Class 9 (relatively less clean). The classification depends on the maximum allowable particle concentration per cubic meter of air.
In addition to particle control, cleanrooms also address other factors like temperature, humidity, electrostatic discharge, and noise levels, which can affect the quality and integrity of the products being manufactured or researched within the cleanroom.
Overall, cleanrooms are critical in industries that require stringent environmental control to ensure product quality, safety, and compliance with regulatory standards. Their design, operation, and maintenance are carefully executed to provide a controlled environment that minimizes the presence of contaminants, making them indispensable in various cutting-edge fields of science and technology.
How can Sentera help to keep these rooms clean?
1. Our latest new development is an air filter monitoring device. With our FIM you can monitor one or 2 filters and receive a warning via email or sms to inform you that the filters need to be cleaned and/or replaced. Via the local Wi-Fi network or a LAN-cable – depending on which version you choose – you can connect the device to SenteraWeb. Via SenteraWeb you can monitor the values, change parameters, log data and schedule ahead the maintenance or replacement of the air filter(s).
2. To control the airflow and positive pressure in the cleanroom you can rely on our differential pressure sensors and differential pressure controllers. The sensors will transmit the measured value (pressure or air flow) proportionally via the analogue output. The controllers can be used to ensure a constant airflow under changing conditions. The output signal can be used to directly control an EC fan or motorised damper or to control an AC fan via a speed controller or frequency inverter. The output is again based on the measured differential pressure, airflow or air velocity. All settings can be adjusted via Modbus RTU. The sensors and controllers are available with or without small display.
For further information, do not hesitate to contact us.
Recently we released the FIM-series, an air filter monitoring device. With these you can choose to monitor one (FIM18) or two (FIM28) air filters at the same time.
The key functions and features of what these air filter monitoring devices do:
Pressure Drop Measurement: Air filters create a resistance to the airflow passing through them. Over time, as the filter collects dust and particulate matter, this resistance increases, resulting in a higher pressure drop across the filter. A filter monitoring device measures the pressure drop across the filter and provides an indication of its condition. If the pressure drop exceeds a certain threshold, it signals that the filter requires maintenance.
Real-time Data and Alerts: Our air filter monitoring devices provide real-time data and alerts, enabling operators or maintenance personnel to monitor the filter condition continuously. They can receive notifications or alarms when the filter needs attention, allowing for timely maintenance actions. These notifications are sent by SMS or e-mail.
Data Logging and Analysis: Filter monitoring devices often record and store historical data on filter performance, pressure drop trends, and other relevant parameters. This data can be analysed to identify patterns, optimize maintenance schedules, or identify potential issues related to the air filtration system.
The last two features are made possible by connecting the FIM to SenteraWeb, our online HVAC-portal. You can connect the device via WiFi only or choose the version where you can choose to connect to SenteraWeb via WiFi or LAN-cable via the integrated Sentera Internet Gateway. This filter monitoring device is designed to be used as standalone article and consequently cannot be integrated into a BMS system.
Air filter monitoring devices can be used in various settings where air quality and the performance of air filters are crucial. Some potential applications where the FIM can be used are:
Residential Homes: Use the device to monitor the air quality and performance of air filters in homes to ensure a healthy living environment, especially for individuals with allergies or respiratory conditions.
Commercial Buildings: Install the monitoring device in office spaces, schools, hospitals, shopping malls, or any commercial building to ensure the air filtration systems are functioning optimally and maintaining good indoor air quality.
Industrial Facilities: Monitor air filters in factories, manufacturing plants, or industrial facilities to ensure that harmful particles, pollutants, or hazardous substances are adequately filtered, maintaining a safe working environment for employees.
HVAC Systems: Integrate the FIM into heating, ventilation, and air conditioning (HVAC) systems to monitor the condition of filters and ensure proper functioning, maximizing energy efficiency and preventing the spread of contaminants.
Laboratories and Cleanrooms: Use the device in sensitive environments like laboratories, cleanrooms, or research facilities to monitor air quality and ensure that strict standards for particle control are maintained.
Hospitality Industry: Implement the monitoring device in hotels, resorts, or other hospitality establishments to monitor air quality in guest rooms and common areas, providing a comfortable and healthy environment for guests.
Data Centers: Install the monitoring device in data centers to ensure proper airflow and filter performance, reducing the risk of equipment damage due to dust or particulate matter.
The specific requirements and recommendations may vary depending on the location, industry, and regulations applicable to each setting.
In summary we can say that by using an air filter monitoring device, facility managers, maintenance personnel, or HVAC technicians can ensure that air filters are functioning optimally, prevent system inefficiencies, maintain good indoor air quality, and extend the lifespan of the filters, ultimately reducing energy costs and improving system performance.
The key functions and features of what these air filter monitoring devices do:
Pressure Drop Measurement: Air filters create a resistance to the airflow passing through them. Over time, as the filter collects dust and particulate matter, this resistance increases, resulting in a higher pressure drop across the filter. A filter monitoring device measures the pressure drop across the filter and provides an indication of its condition. If the pressure drop exceeds a certain threshold, it signals that the filter requires maintenance.
Real-time Data and Alerts: Our air filter monitoring devices provide real-time data and alerts, enabling operators or maintenance personnel to monitor the filter condition continuously. They can receive notifications or alarms when the filter needs attention, allowing for timely maintenance actions. These notifications are sent by SMS or e-mail.
Data Logging and Analysis: Filter monitoring devices often record and store historical data on filter performance, pressure drop trends, and other relevant parameters. This data can be analysed to identify patterns, optimize maintenance schedules, or identify potential issues related to the air filtration system.
The last two features are made possible by connecting the FIM to SenteraWeb, our online HVAC-portal. You can connect the device via WiFi only or choose the version where you can choose to connect to SenteraWeb via WiFi or LAN-cable via the integrated Sentera Internet Gateway. This filter monitoring device is designed to be used as standalone article and consequently cannot be integrated into a BMS system.
Air filter monitoring devices can be used in various settings where air quality and the performance of air filters are crucial. Some potential applications where the FIM can be used are:
Residential Homes: Use the device to monitor the air quality and performance of air filters in homes to ensure a healthy living environment, especially for individuals with allergies or respiratory conditions.
Commercial Buildings: Install the monitoring device in office spaces, schools, hospitals, shopping malls, or any commercial building to ensure the air filtration systems are functioning optimally and maintaining good indoor air quality.
Industrial Facilities: Monitor air filters in factories, manufacturing plants, or industrial facilities to ensure that harmful particles, pollutants, or hazardous substances are adequately filtered, maintaining a safe working environment for employees.
HVAC Systems: Integrate the FIM into heating, ventilation, and air conditioning (HVAC) systems to monitor the condition of filters and ensure proper functioning, maximizing energy efficiency and preventing the spread of contaminants.
Laboratories and Cleanrooms: Use the device in sensitive environments like laboratories, cleanrooms, or research facilities to monitor air quality and ensure that strict standards for particle control are maintained.
Hospitality Industry: Implement the monitoring device in hotels, resorts, or other hospitality establishments to monitor air quality in guest rooms and common areas, providing a comfortable and healthy environment for guests.
Data Centers: Install the monitoring device in data centers to ensure proper airflow and filter performance, reducing the risk of equipment damage due to dust or particulate matter.
The specific requirements and recommendations may vary depending on the location, industry, and regulations applicable to each setting.
In summary we can say that by using an air filter monitoring device, facility managers, maintenance personnel, or HVAC technicians can ensure that air filters are functioning optimally, prevent system inefficiencies, maintain good indoor air quality, and extend the lifespan of the filters, ultimately reducing energy costs and improving system performance.
The choice of controller type is important. Opting for manual control means you and not a device are acting as the controller - you make the decisions about what control actions to take. Automatic control imitates the actions you would take during manual control. The reason we use automatic controls is that we do not have the time or desire, or perhaps the ability, to constantly monitor a process to maintain the desired result.
Temperature is a major factor in comfort ventilation and is readily measured and controlled. HVAC systems are generally designed to handle peak cooling or heating loads that seldom, if ever, take place, so we must provide controls that can regulate the system’s output to meet the actual cooling or heating load at a given time.
If you have a voltage controllable AC-motor, and want to control fan speed based on temperature, we can offer our brand new GTH21-series. The controller is available in 7,5 A and 10 A and is an extension to our already well-known GTH-1-series. The functionalities are the same but the electronics used are newer and it has Modbus RTU communication, which our GTH-1 does not have.
Below is a list of the most important characteristics of our GTH21:
1. Transformer technology: It is highly reliable and durable, producing a motor voltage with a smooth sinusoidal waveform. This results in exceptionally quiet motor operation and an extended service life.
2. Temperature-based control: The GTH21-series offers the ability to control single-phase motors in five steps based on the measured ambient temperature. The PT500 temperature probe is connected directly to the controller and placed in the desired area, thus optimising the motor speed for efficient operation depending on the environmental conditions. Motor speed is controlled by varying the output voltage.
3. Heating or Cooling mode: In heating mode, the fan is activated when the measured temperature drops below the set temperature. When the measured temperature is higher than the selected temperature, the fan is deactivated. In cooling mode, the functionality is inversed. You can switch between modes by using a jumper.
4. Automatic and manual control: The controllers come with both automatic and manual modes, giving users the flexibility to choose between automated temperature-based control and manual adjustment.
5. Voltage output variation: The controllers regulate the rotational speed of single-phase voltage controllable motors by varying the output voltage in accordance to the measured ambient temperature. This dynamic adjustment helps maintain optimal performance based on changing conditions.
6. Relay output or unregulated output for valve control: The device is equipped with a relay output that responds to the measured temperature. This output can be utilised to control a valve, making it suitable for use in both cooling and heating systems. This capability contributes to maintaining consistent temperature levels.
7. Modbus compatibility: The GTH21 controllers can be fully controlled using the Modbus protocol. Modbus is a common communication protocol, allowing for seamless integration and remote management.
8. Enclosure and protection: The controllers' enclosure is made of sheet steel, providing a robust and durable housing. The enclosure's IP54 protection rating ensures resistance against the ingress of water and dust, making the controllers suitable for various environments.
Temperature is a major factor in comfort ventilation and is readily measured and controlled. HVAC systems are generally designed to handle peak cooling or heating loads that seldom, if ever, take place, so we must provide controls that can regulate the system’s output to meet the actual cooling or heating load at a given time.
If you have a voltage controllable AC-motor, and want to control fan speed based on temperature, we can offer our brand new GTH21-series. The controller is available in 7,5 A and 10 A and is an extension to our already well-known GTH-1-series. The functionalities are the same but the electronics used are newer and it has Modbus RTU communication, which our GTH-1 does not have.
Below is a list of the most important characteristics of our GTH21:
1. Transformer technology: It is highly reliable and durable, producing a motor voltage with a smooth sinusoidal waveform. This results in exceptionally quiet motor operation and an extended service life.
2. Temperature-based control: The GTH21-series offers the ability to control single-phase motors in five steps based on the measured ambient temperature. The PT500 temperature probe is connected directly to the controller and placed in the desired area, thus optimising the motor speed for efficient operation depending on the environmental conditions. Motor speed is controlled by varying the output voltage.
3. Heating or Cooling mode: In heating mode, the fan is activated when the measured temperature drops below the set temperature. When the measured temperature is higher than the selected temperature, the fan is deactivated. In cooling mode, the functionality is inversed. You can switch between modes by using a jumper.
4. Automatic and manual control: The controllers come with both automatic and manual modes, giving users the flexibility to choose between automated temperature-based control and manual adjustment.
5. Voltage output variation: The controllers regulate the rotational speed of single-phase voltage controllable motors by varying the output voltage in accordance to the measured ambient temperature. This dynamic adjustment helps maintain optimal performance based on changing conditions.
6. Relay output or unregulated output for valve control: The device is equipped with a relay output that responds to the measured temperature. This output can be utilised to control a valve, making it suitable for use in both cooling and heating systems. This capability contributes to maintaining consistent temperature levels.
7. Modbus compatibility: The GTH21 controllers can be fully controlled using the Modbus protocol. Modbus is a common communication protocol, allowing for seamless integration and remote management.
8. Enclosure and protection: The controllers' enclosure is made of sheet steel, providing a robust and durable housing. The enclosure's IP54 protection rating ensures resistance against the ingress of water and dust, making the controllers suitable for various environments.
Greenhouses can utilise natural ventilation methods, such as roof vents, side vents, and louvers, to control airflow. These openings allow warm air to rise and escape, while cooler air is drawn in through the sides or lower vents. This passive approach can be effective in moderating temperatures but may not be sufficient in extreme weather conditions.
In addition to natural ventilation, many greenhouses employ forced ventilation systems. These systems can help maintain consistent temperature and humidity levels, especially during hot or cold periods. Many modern greenhouses use automated control systems to monitor and adjust environmental conditions. These systems can be programmed to operate fans, vents, and other ventilation equipment based on pre-set parameters for temperature, humidity, and CO2 levels.
Maintaining the right temperature is crucial for plant health. Greenhouses can overheat during the day, especially in sunny conditions, and become too cold at night. Ventilation helps regulate temperature by allowing warm air to escape and cooler air to enter, preventing temperature extremes.
Humidity levels in a greenhouse affect plant transpiration, disease susceptibility, and overall plant health. Proper ventilation helps control humidity by removing excess moisture and maintaining the desired humidity range.
Adequate CO2 is essential for photosynthesis. Greenhouse ventilation ensures a sufficient supply of fresh air with CO2 to support plant growth.
Exhaust fans are commonly used in greenhouses to remove hot, stagnant air. These fans are usually placed near the roof or gable ends of the greenhouse to draw out warm air, ensuring proper air exchange. Some exhaust fans are equipped with automatic shutters to prevent the entry of pests or extreme weather conditions.
Appropriate distribution of air within the greenhouse is essential to ensure that all plants receive the same environmental conditions. Circulation fans used to even out temperature and humidity, as well as the forced air circulation inside, can affect the overall ventilation strategy. Proper airflow management helps prevent stagnation and ensures an optimal climate.
Correct ventilation is essential for creating a healthy and productive environment in a greenhouse. It helps prevent issues like mould, diseases, and excessive humidity, while also allowing for the efficient exchange of gases necessary for plant growth. The specific ventilation methods used will depend on the type of greenhouse, the crops being grown, and the local climate conditions. Greenhouse managers and growers continuously monitor these parameters and adjust ventilation systems accordingly. Properly managing these variables through ventilation is essential to create a controlled and favorable environment for optimal plant growth and crop production.
Sentera offers a large selection of sensors suitable for this kind of application. They come with a variety of power supplies and switchable output types to work with the majority of devices. Our intelligent sensors can even directly control EC fans or damper actuators.
If your AC fan needs to be controlled based on temperature, use one of our temperature-based transformer fan speed controllers or variable fan speed controllers. If you want to be able to remotely monitor, log data, or change parameters, you can connect your sensor or controller to SenteraWeb, our online HVAC portal. This can be done by simply adding a Sentera internet gateway.
If you require stand-alone solutions that may be used or required repeatedly, please contact us. We can discuss your circumstances and determine whether to develop a specialised solution with specific firmware.
In addition to natural ventilation, many greenhouses employ forced ventilation systems. These systems can help maintain consistent temperature and humidity levels, especially during hot or cold periods. Many modern greenhouses use automated control systems to monitor and adjust environmental conditions. These systems can be programmed to operate fans, vents, and other ventilation equipment based on pre-set parameters for temperature, humidity, and CO2 levels.
Maintaining the right temperature is crucial for plant health. Greenhouses can overheat during the day, especially in sunny conditions, and become too cold at night. Ventilation helps regulate temperature by allowing warm air to escape and cooler air to enter, preventing temperature extremes.
Humidity levels in a greenhouse affect plant transpiration, disease susceptibility, and overall plant health. Proper ventilation helps control humidity by removing excess moisture and maintaining the desired humidity range.
Adequate CO2 is essential for photosynthesis. Greenhouse ventilation ensures a sufficient supply of fresh air with CO2 to support plant growth.
Exhaust fans are commonly used in greenhouses to remove hot, stagnant air. These fans are usually placed near the roof or gable ends of the greenhouse to draw out warm air, ensuring proper air exchange. Some exhaust fans are equipped with automatic shutters to prevent the entry of pests or extreme weather conditions.
Appropriate distribution of air within the greenhouse is essential to ensure that all plants receive the same environmental conditions. Circulation fans used to even out temperature and humidity, as well as the forced air circulation inside, can affect the overall ventilation strategy. Proper airflow management helps prevent stagnation and ensures an optimal climate.
Correct ventilation is essential for creating a healthy and productive environment in a greenhouse. It helps prevent issues like mould, diseases, and excessive humidity, while also allowing for the efficient exchange of gases necessary for plant growth. The specific ventilation methods used will depend on the type of greenhouse, the crops being grown, and the local climate conditions. Greenhouse managers and growers continuously monitor these parameters and adjust ventilation systems accordingly. Properly managing these variables through ventilation is essential to create a controlled and favorable environment for optimal plant growth and crop production.
Sentera offers a large selection of sensors suitable for this kind of application. They come with a variety of power supplies and switchable output types to work with the majority of devices. Our intelligent sensors can even directly control EC fans or damper actuators.
If your AC fan needs to be controlled based on temperature, use one of our temperature-based transformer fan speed controllers or variable fan speed controllers. If you want to be able to remotely monitor, log data, or change parameters, you can connect your sensor or controller to SenteraWeb, our online HVAC portal. This can be done by simply adding a Sentera internet gateway.
If you require stand-alone solutions that may be used or required repeatedly, please contact us. We can discuss your circumstances and determine whether to develop a specialised solution with specific firmware.
In general, cars with combustion engines primarily emit carbon dioxide (CO2) and carbon monoxide (CO) as exhaust gases. However, the relative amounts of each emitted gas can vary depending on several factors such as the type of fuel used, the efficiency of the engine, and the driving conditions. Due to their typically low ceiling, underground and enclosed car parks present a particular challenge to ventilation systems. Such a smart ventilation system must prevent the accumulation of toxic gases from motor exhausts in a garage. Toxic gas sensors are optimized to detect and measure these toxic gases in parking garages.
Typically, carbon dioxide (CO2) is emitted in larger quantities compared to carbon monoxide (CO) in combustion engine exhaust. This is because carbon dioxide is a byproduct of the complete combustion of hydrocarbon fuels such as gasoline or diesel. On the other hand, carbon monoxide is produced when there is incomplete combustion of fuel due to insufficient oxygen supply, inefficient combustion, or engine malfunction.
In terms of comparison, carbon dioxide emissions from combustion engines are generally much higher than carbon monoxide emissions. However, it's important to note that carbon monoxide is a more potent pollutant in terms of immediate health effects, as it can interfere with the body's ability to transport oxygen. Therefore, even though CO2 emissions are higher and therefore easier to detect, CO emissions are more concerning in terms of immediate health impacts. For this reason, CO sensors are sometimes prescribed in local regulations for monitoring air quality in parking garages. However, controlling a ventilation system in parking garages can be done much more efficiently based on CO2 measurements. When vehicles with combustion engines are active, CO2 sensors will be the first to detect poor air quality, long before the CO sensors notice increased values. Based on the CO2 measurement, the fans can be controlled to supply fresh air and remove toxic gases in a timely manner.
The risk of Carbon Monoxide (CO), the silent killer
Toxic or noxious gases are gases that are harmful to living things. Carbon monoxide (CO) is a colourless, odourless and highly poisonous gas. It is sometimes referred to as the ‘silent killer’. It is emitted by vehicle engines together with CO2. When carbon monoxide molecules are released into open air, they typically undergo oxidation reactions. It does dissipate relatively quickly when exposed to fresh air. In the presence of oxygen (O2), carbon monoxide can react to form carbon dioxide (CO2). The reaction can be represented as: 2 CO + O2 → 2 CO2. When CO mixes with air in an underground parking garage, it will initially further increase CO2 concentrations. When released into open spaces or outdoor environments, CO tends to disperse and mix with the surrounding air, reducing its concentration to safer levels.
However, in enclosed or poorly ventilated spaces like parking garages, CO can accumulate if there is ongoing emission from vehicle exhaust or other sources without adequate ventilation. Without proper airflow, the gas may linger and build up to dangerous concentrations, posing health risks to individuals in those areas, which can lead to headaches, dizziness, nausea, and in severe cases, it can be life threatening. When CO is breathed in, it gets into the blood stream, attaching itself to red blood cells, which can then no longer carry oxygen. We humans need oxygen to break down food in order to get the energy we need to survive, to move our muscles or even to just think. Symptoms of CO poisoning are headaches, drowsiness, visual problems, breathlessness, nausea and even stomach and chest pains. To prevent or reduce high concentrations of carbon monoxide in an enclosed environment as an underground parking, fresh air should be supplied to wash away the carbon monoxide.
Regular monitoring of CO levels in parking garages is crucial for maintaining safety standards and safeguarding occupants' health. It aids in the timely detection of potential leaks or inadequate ventilation, enabling interventions to mitigate health risks associated with CO exposure. Depending on local regulations and standards, there might be specific requirements for monitoring CO levels in enclosed spaces like parking garages. Regular monitoring helps ensure compliance with these regulations.
However, in enclosed or poorly ventilated spaces like parking garages, CO can accumulate if there is ongoing emission from vehicle exhaust or other sources without adequate ventilation. Without proper airflow, the gas may linger and build up to dangerous concentrations, posing health risks to individuals in those areas, which can lead to headaches, dizziness, nausea, and in severe cases, it can be life threatening. When CO is breathed in, it gets into the blood stream, attaching itself to red blood cells, which can then no longer carry oxygen. We humans need oxygen to break down food in order to get the energy we need to survive, to move our muscles or even to just think. Symptoms of CO poisoning are headaches, drowsiness, visual problems, breathlessness, nausea and even stomach and chest pains. To prevent or reduce high concentrations of carbon monoxide in an enclosed environment as an underground parking, fresh air should be supplied to wash away the carbon monoxide.
Regular monitoring of CO levels in parking garages is crucial for maintaining safety standards and safeguarding occupants' health. It aids in the timely detection of potential leaks or inadequate ventilation, enabling interventions to mitigate health risks associated with CO exposure. Depending on local regulations and standards, there might be specific requirements for monitoring CO levels in enclosed spaces like parking garages. Regular monitoring helps ensure compliance with these regulations.
Where to install the CO sensors?
When positioning carbon monoxide (CO) sensors in indoor spaces such as underground parking garages, it's generally recommended to install them at a height where they can effectively detect CO concentrations that pose a risk to occupants. Unlike LPG, which is denser than air and tends to accumulate near the ground, CO is roughly the same density as air and distributes evenly throughout the space. Therefore, CO sensors are usually installed at breathing height, roughly between 1.2 to 1.8 meters above the ground, as this is where people typically breathe.
Understanding the airflow patterns within the parking garage is crucial for effective sensor placement. If there are specific areas where CO buildup is more likely due to poor ventilation or stagnant air, sensors should be strategically located to monitor these areas. Sensors should be placed in locations free from obstructions that could interfere with the flow of CO to the sensor. Avoid placing sensors near walls, corners, or behind objects that could block airflow and result in inaccurate readings.
Local building codes or regulations may specify requirements for the placement of CO sensors in parking garages or other indoor spaces. Compliance with these regulations is essential for ensuring the safety of occupants and avoiding potential penalties.
The Role of Carbon Dioxide (CO2) monitoring
Carbon Dioxide or CO2 is a greenhouse gas that is natural and harmless in small quantities. It is necessary for the survival of life on earth. CO2 is not only the result from burning fossil fuels. Indoor carbon dioxide concentrations are the result of a combination of outdoor CO2, indoor breathing and the ventilation rate of the building. CO2 is evacuated by supplying fresh air. While carbon dioxide (CO2) isn't as immediately harmful as CO, it plays a significant role in assessing overall indoor air quality and ventilation system effectiveness.
When a motor combusts fuel, the primary products of combustion are carbon dioxide (CO2) and water vapor (H2O) in the presence of sufficient oxygen. The amount of CO2 released during combustion is generally higher than the amount of carbon monoxide (CO) produced. Under normal operating conditions, modern engines and combustion systems are designed to optimise the combustion process to produce as much CO2 as possible through complete combustion while minimising the production of carbon monoxide (CO) and other harmful emissions. However, in situations where combustion is not efficient or there's a lack of proper air-to-fuel ratio, higher levels of carbon monoxide can be generated along with other pollutants.
Elevated CO2 levels can cause discomfort, leading to headaches and a feeling of stuffiness. Monitoring CO2 levels ensures adequate ventilation and helps maintain acceptable indoor air quality for the comfort and well-being of individuals using or working in the parking garage. To prevent or reduce high concentrations of carbon dioxide in an enclosed environment as an underground parking, fresh air should be supplied to wash away the carbon dioxide. Indoor CO2 levels between 400-1.000 ppm are acceptable. When the values exceed this range, additional ventilation is required.
Carbon Dioxide or CO2 is a greenhouse gas that is natural and harmless in small quantities. It is necessary for the survival of life on earth. CO2 is not only the result from burning fossil fuels. Indoor carbon dioxide concentrations are the result of a combination of outdoor CO2, indoor breathing and the ventilation rate of the building. CO2 is evacuated by supplying fresh air. While carbon dioxide (CO2) isn't as immediately harmful as CO, it plays a significant role in assessing overall indoor air quality and ventilation system effectiveness.
When a motor combusts fuel, the primary products of combustion are carbon dioxide (CO2) and water vapor (H2O) in the presence of sufficient oxygen. The amount of CO2 released during combustion is generally higher than the amount of carbon monoxide (CO) produced. Under normal operating conditions, modern engines and combustion systems are designed to optimise the combustion process to produce as much CO2 as possible through complete combustion while minimising the production of carbon monoxide (CO) and other harmful emissions. However, in situations where combustion is not efficient or there's a lack of proper air-to-fuel ratio, higher levels of carbon monoxide can be generated along with other pollutants.
Elevated CO2 levels can cause discomfort, leading to headaches and a feeling of stuffiness. Monitoring CO2 levels ensures adequate ventilation and helps maintain acceptable indoor air quality for the comfort and well-being of individuals using or working in the parking garage. To prevent or reduce high concentrations of carbon dioxide in an enclosed environment as an underground parking, fresh air should be supplied to wash away the carbon dioxide. Indoor CO2 levels between 400-1.000 ppm are acceptable. When the values exceed this range, additional ventilation is required.
LPG measurements to detect dangerous situations
LPG or Liquefied Petroleum Gas is highly flammable, and in the confined space of an underground parking garage, any leakage can pose a significant fire hazard. LPG is commonly used as a fuel for vehicles and as a heating source. In underground parking garages, there's a risk of leaks from vehicles or from the storage systems themselves. Vehicles with an LPG tank are therefore not allowed in all parking garages. Measuring LPG levels helps to detect any leaks promptly and to enable the monitoring of potentially dangerous concentrations.
Underground parking garages are often used by a large number of people, including drivers, pedestrians, and maintenance staff. Monitoring LPG levels ensures the safety of occupants by alerting them to any hazardous conditions and allowing for timely evacuation if necessary. Many jurisdictions have regulations governing the use and storage of LPG in public spaces such as parking garages. Regular monitoring and measurement of LPG levels help ensure compliance with these regulations, reducing the risk of fires and explosions, including the risk of penalties and liability in case of accidents.
When measuring LPG levels in an underground parking garage, it's essential to position the sensors at a height where the gas concentration is likely to be most representative of the overall environment and where it poses the most significant risk to occupants. Generally, this means placing the sensors approximately 30 cm above floor level. LPG is denser than air, meaning it tends to settle near the ground rather than dispersing upwards. Placing sensors closer to the ground allows for more accurate detection of any LPG leaks, as the concentration will be highest near the floor where the gas accumulates.
However, it's essential to consider the specific layout and ventilation characteristics of the parking garage when determining sensor placement. For example, if there are ventilation ducts or fans that could affect gas dispersion patterns, sensors may need to be strategically placed to account for these factors. Consulting with safety experts or engineers familiar with gas detection systems can help ensure the most effective placement of LPG sensors in an underground parking garage.
CO2 based ventilation control in parking garages
Given the immediate health risks associated with high CO concentrations, prioritising CO measurement is often recommended in closed parking garages. CO can quickly reach hazardous levels in confined spaces, necessitating vigilant monitoring to prevent potential health hazards. However, CO2 measurement remains valuable for assessing overall indoor air quality and ventilation system efficiency. Since more CO2 is released during combustion processes, CO2 will often be detected faster than CO presence in the air. Both CO and CO2 measurements work synergistically to provide insights into the environment's health and safety aspects.
Air quality is the basis on which a ventilation system is controlled. When the air quality is insufficient, more ventilation is required. The fresh air will flush out the toxic gases. CO2 sensors provide a more accurate indication of air quality and will respond much faster than CO sensors. Controlling jet fans in a parking garage with CO sensors will lead to delayed responses, resulting in poor air quality and insufficient ventilation.
We can conclude that CO2 sensors are needed to guarantee good air quality in an underground parking garage. When vehicles with combustion engines are active, CO2 sensors will be the first to detect poor air quality, long before the CO sensors notice increased values. Based on the CO2 measurement, the fans can be controlled to supply fresh air and remove toxic gases in a timely manner. CO sensors can be used to identify dangerous situations in case the ventilation system does not function correctly.
We at Sentera offer sensors that are specifically designed for installation in such enclosed spaces.
The SPRKM-R is a multifunctional transmitter that measures CO, temperature, relative humidity as well as LPG.
Our outdoor CO2 sensors are created as such that they can be applied in harsh environments, providing IP65 protection against ingress of water and dust.
The SPRKM-R is a multifunctional transmitter that measures CO, temperature, relative humidity as well as LPG.
Our outdoor CO2 sensors are created as such that they can be applied in harsh environments, providing IP65 protection against ingress of water and dust.
Both AC and EC motors are electrical motors. Electrical motors play a crucial role in daily life, as they are involved in powering countless devices and systems we rely on. In household applications, they can be found in refrigerators, washing machines, air conditioners, vacuum cleaners, etc. HVAC systems rely on electrical motors to circulate air, regulate temperature and maintain comfort in homes, offices and other buildings. Also in transportation, industry and manufacturing electrical motors play a crucial role. In this article we explain the differences between AC motors and EC motors in an understandable way. The options for controlling an AC motor and the advantages and disadvantages of the technologies mentioned are briefly discussed.
Electric motors work based on the interaction between magnetism and electric currents
An electric motor is a machine that converts electrical energy into mechanical energy. Electrical energy is mainly converted by the motor into rotary motion. The electrical energy or power is expressed in kW, while the rotary motion is expressed in rpm. So the electrical power [kW] is converted by the motor into rotary motion [rpm].
Electric motors work based on the interaction between magnetism and electric currents
An electric motor is a machine that converts electrical energy into mechanical energy. Electrical energy is mainly converted by the motor into rotary motion. The electrical energy or power is expressed in kW, while the rotary motion is expressed in rpm. So the electrical power [kW] is converted by the motor into rotary motion [rpm].
But that is not enough. Magnetism is also required in addition to the electrical energy. Some motors use permanent magnets, other motor types create their own magnetic fields using coils and electric currents.
An electric motor works based on a dynamic interplay of magnetic forces. When an electrical current is applied, it generates a magnetic field that interacts with magnets situated on a rotating component. This interaction induces rotary motion, exemplifying the conversion of electrical energy into mechanical motion. The motor serves as a sophisticated mechanism wherein the orchestrated synergy between electricity and magnetism facilitates controlled and purposeful rotational movement, underpinning a wide array of applications in all industries, including HVAC industry.
A motor is made up of a stator and a rotor. The stator is the static part of the motor – the stationary part used to mount the motor to the air duct or installation. The rotor is the rotating part on which the motor shaft is mounted. In a fan, the fan blades are mounted on this motor shaft (on the rotor). The rotor usually has a cylindrical shape. In the stator, a magnetic field is generated through electromagnetism. The electric current flows through the motor winding in the stator and generates a magnetic field. Since it concerns alternating voltage and several windings are used, this magnetic field revolves around the rotor. The rotor follows this rotating magnetic field. You can compare it to magnets that attract each other.
An electric motor works based on a dynamic interplay of magnetic forces. When an electrical current is applied, it generates a magnetic field that interacts with magnets situated on a rotating component. This interaction induces rotary motion, exemplifying the conversion of electrical energy into mechanical motion. The motor serves as a sophisticated mechanism wherein the orchestrated synergy between electricity and magnetism facilitates controlled and purposeful rotational movement, underpinning a wide array of applications in all industries, including HVAC industry.
A motor is made up of a stator and a rotor. The stator is the static part of the motor – the stationary part used to mount the motor to the air duct or installation. The rotor is the rotating part on which the motor shaft is mounted. In a fan, the fan blades are mounted on this motor shaft (on the rotor). The rotor usually has a cylindrical shape. In the stator, a magnetic field is generated through electromagnetism. The electric current flows through the motor winding in the stator and generates a magnetic field. Since it concerns alternating voltage and several windings are used, this magnetic field revolves around the rotor. The rotor follows this rotating magnetic field. You can compare it to magnets that attract each other.
During the process of converting electrical energy into mechanical energy, a part of the energy is lost. These energy losses are caused by heat generation, mechanical friction and other electrical losses in the motor. The efficiency of an electric motor tells you what part of the absorbed energy is available at the motor shaft. The efficiency is usually indicated on the nameplate by the symbol η expressed in %. η = 85% means that 15% of the absorbed electrical energy is lost. The higher the efficiency of the motor, the smaller the losses and the more energy is converted into torque. The force with which the rotational movement is performed is called the torque and is expressed in Nm.
AC motors - Asynchronous vs synchronous motor
AC motors are the standard for industrial applications. This type of motor is also regularly used in the HVAC sector, especially with larger capacities. AC motors are very reliable, robust and easy to maintain. We distinguish between synchronous and asynchronous AC motors.
Asynchronous motor
The standard asynchronous motor is the simplest and most widely used electric motor in HVAC and in industrial automation. It is a proven concept that is cost-effective, robust and reliable. Asynchronous motors are relatively easy to maintain and in many cases their speed can be easily controlled. Thanks to technological progress, more energy-efficient solutions are now available, but these also come at a price.
The standard asynchronous motor is the simplest and most widely used electric motor in HVAC and in industrial automation. It is a proven concept that is cost-effective, robust and reliable. Asynchronous motors are relatively easy to maintain and in many cases their speed can be easily controlled. Thanks to technological progress, more energy-efficient solutions are now available, but these also come at a price.
The working principle of an asynchronous motor is a bit more difficult to explain in a simple way. The asynchronous motor does not have a rotor with permanent magnets; it's magnetic field is created by induction. To make this possible, the rotor is composed of electrical conductors. These conductive rods are usually made of aluminium or copper. They are mounted in the cylindrical rotor and are connected at both ends by short-circuit rings. The whole has a cage-like shape – hence the name squirrel cage rotor. Due to the principle of induction (Faraday's law), electric current flows through these conductors. Due to this reason, an asynchronous motor is also called an induction motor. This rotor current creates a magnetic field that interacts with the stator field, causing the motor to rotate.
Unlike a synchronous motor, an asynchronous motor will always rotate slower than the stator magnetic field. This difference is called the slip. Due to this difference, a reverse current is induced in the rotor of the asynchronous motor. The greater the load, the greater the difference (slip). The rotor accelerates until the magnitude of the induced rotor current and motor torque balances the load on the motor shaft. Since there is no induced rotor current (no torque) at synchronous speed, an induction motor always runs slower than synchronous speed.
Unlike a synchronous motor, an asynchronous motor will always rotate slower than the stator magnetic field. This difference is called the slip. Due to this difference, a reverse current is induced in the rotor of the asynchronous motor. The greater the load, the greater the difference (slip). The rotor accelerates until the magnitude of the induced rotor current and motor torque balances the load on the motor shaft. Since there is no induced rotor current (no torque) at synchronous speed, an induction motor always runs slower than synchronous speed.
Synchronous motors
Synchronous AC motors are technologically more complex than asynchronous motors. They use permanent magnets, which makes them more expensive. The big advantage is their lower energy consumption. A synchronous motor is less easy to control than an asynchronous motor. Usually a specific type of frequency controller is required to control them. Synchronous motors cannot be controlled with a transformer speed controller nor with an electronic speed controller.
As mentioned above, a rotating magnetic field is created in the stator. A synchronous motor has a rotor made up of permanent magnets. Magnetic opposites attract each other. The magnets of the rotor will therefore follow the rotating stator field exactly (synchronously), regardless of the load.
Speed controllers for AC motors
Synchronous motors generally consume less energy than asynchronous motors, but can only be used in combination with a frequency converter. Asynchronous motors offer the choice of whether or not to be controlled by a speed controller. Speed controllers help to reduce mechanical shock during start-up. Thanks to speed controllers, many applications can be controlled more comfortably and precisely. Just think of demand-driven ventilation where speed controllers optimize the airflow and combine good indoor air quality with energy savings.
In HVAC applications, fans with asynchronous motors can be controlled with a frequency converter or with a fan speed controller. Both have their pros and cons. A frequency controller offers the most accurate control and is energy efficient. A fan speed controller is cheaper and much easier to install and use.
A frequency inverter will optimize both the motor voltage and the frequency of the motor current via pulse width modulation. This requires IGBTs. Insulated Gate Bipolar Transistors are high-performance electronic components that can switch high-power electrical currents at very high frequencies. This technology enables optimum engine control, but it is not cheap. Usually a V/f or scalar frequency controller is chosen to control fans. A scalar frequency converter keeps the ratio V/f constant (constant torque) over the entire speed range. These are the simplest frequency converters given the small amount of motor data required by the drive. Only a limited configuration is necessary to control the motor. V/f is the only control method that allows multiple motors to be controlled by one frequency converter. In such applications, all motors start and stop at the same time and follow the same speed reference.
Unlike a frequency converter, a fan speed controller will only vary the motor voltage. This type of speed controller is only suitable for voltage controllable motors and can therefore be used in applications where the torque decreases with speed, for example controlling fans. The big advantage of this type of controller is the simple operation and the cost price. No configuration is needed; once everything is connected, the fan can be controlled immediately. The construction of a fan speed controller is much simpler than that of a variable speed drive. This also translates into the cost. A number of different technologies can be used for fan speed controllers – each with their own specific advantages and disadvantages. The most commonly used technologies are: transformer speed controllers (5-step controller) or electronic fan speed controllers (TRIAC phase angle control).
Speed controllers for AC motors
Synchronous motors generally consume less energy than asynchronous motors, but can only be used in combination with a frequency converter. Asynchronous motors offer the choice of whether or not to be controlled by a speed controller. Speed controllers help to reduce mechanical shock during start-up. Thanks to speed controllers, many applications can be controlled more comfortably and precisely. Just think of demand-driven ventilation where speed controllers optimize the airflow and combine good indoor air quality with energy savings.
In HVAC applications, fans with asynchronous motors can be controlled with a frequency converter or with a fan speed controller. Both have their pros and cons. A frequency controller offers the most accurate control and is energy efficient. A fan speed controller is cheaper and much easier to install and use.
A frequency inverter will optimize both the motor voltage and the frequency of the motor current via pulse width modulation. This requires IGBTs. Insulated Gate Bipolar Transistors are high-performance electronic components that can switch high-power electrical currents at very high frequencies. This technology enables optimum engine control, but it is not cheap. Usually a V/f or scalar frequency controller is chosen to control fans. A scalar frequency converter keeps the ratio V/f constant (constant torque) over the entire speed range. These are the simplest frequency converters given the small amount of motor data required by the drive. Only a limited configuration is necessary to control the motor. V/f is the only control method that allows multiple motors to be controlled by one frequency converter. In such applications, all motors start and stop at the same time and follow the same speed reference.
Unlike a frequency converter, a fan speed controller will only vary the motor voltage. This type of speed controller is only suitable for voltage controllable motors and can therefore be used in applications where the torque decreases with speed, for example controlling fans. The big advantage of this type of controller is the simple operation and the cost price. No configuration is needed; once everything is connected, the fan can be controlled immediately. The construction of a fan speed controller is much simpler than that of a variable speed drive. This also translates into the cost. A number of different technologies can be used for fan speed controllers – each with their own specific advantages and disadvantages. The most commonly used technologies are: transformer speed controllers (5-step controller) or electronic fan speed controllers (TRIAC phase angle control).
How to set the requested AC fan speed?
Regardless of the type of AC speed controller or frequency inverter, the user must be able to specify the desired speed. This can be done in different ways. On the one hand, we distinguish speed controllers where the controls are built-in in the device itself, on the other hand, devices that require an external electrical signal with which the desired speed can be set. This external signal can be analogue (e.g. 0-10 Volt) or digital (e.g. Modbus RTU communication). The possibilities for setting the desired speed via an external electrical signal are discussed in detail in the article on potentiometers.
EC motors – motors with built-in speed controller
Brushless DC electric motors are also referred to as Electronically Commutated motors (EC motors). They are synchronous motors that are driven by direct current via a built-in (speed) controller. However, EC motors are connected to alternating current (mains voltage). This alternating current is internally converted into direct current with which the integrated controller controls the motor.
EC motors usually have a rotor made of permanent magnets that revolve around a stator. The built-in regulator contains a rectifier that converts the AC supply voltage into direct current (DC). The integrated regulator then sends the right amount of current, in the right direction, at the right time, through the windings in the stator. This creates a rotating magnetic field in the stator, which drives the rotor with permanent magnets. The position of each rotor magnet is determined using Hall sensors. The appropriate magnets are sequentially attracted to the magnetic poles in the stator. At the same time, the rest of the stator windings are charged with the reversed polarity. These attractive and repulsive forces combine to achieve smooth rotation and produce the optimum torque. Because this is all done electronically, precise motor monitoring and control is possible. An EC motor can therefore be regarded as the combination of motor and speed controller in one housing.
EC motors are usually more expensive compared to AC motors, but they offer some advantages. The main ones are: a high torque-to-weight ratio due to their more compact construction and lower energy consumption compared to AC motors. The permanent magnets and integrated electronics make this type of motor more expensive. The motor and the fan speed controller are combined in one housing. If the EC motor can be directly controlled via Modbus communication, all motor parameters such as temperature in the motor windings, power consumption, rotational speed, hour counter, etc. can be read remotely. The commissioning might be more complicated, but once installed, this solution offers more options - especially in terms of integration into BMS systems or smart ventilation systems.
EC motors – motors with built-in speed controller
Brushless DC electric motors are also referred to as Electronically Commutated motors (EC motors). They are synchronous motors that are driven by direct current via a built-in (speed) controller. However, EC motors are connected to alternating current (mains voltage). This alternating current is internally converted into direct current with which the integrated controller controls the motor.
EC motors usually have a rotor made of permanent magnets that revolve around a stator. The built-in regulator contains a rectifier that converts the AC supply voltage into direct current (DC). The integrated regulator then sends the right amount of current, in the right direction, at the right time, through the windings in the stator. This creates a rotating magnetic field in the stator, which drives the rotor with permanent magnets. The position of each rotor magnet is determined using Hall sensors. The appropriate magnets are sequentially attracted to the magnetic poles in the stator. At the same time, the rest of the stator windings are charged with the reversed polarity. These attractive and repulsive forces combine to achieve smooth rotation and produce the optimum torque. Because this is all done electronically, precise motor monitoring and control is possible. An EC motor can therefore be regarded as the combination of motor and speed controller in one housing.
EC motors are usually more expensive compared to AC motors, but they offer some advantages. The main ones are: a high torque-to-weight ratio due to their more compact construction and lower energy consumption compared to AC motors. The permanent magnets and integrated electronics make this type of motor more expensive. The motor and the fan speed controller are combined in one housing. If the EC motor can be directly controlled via Modbus communication, all motor parameters such as temperature in the motor windings, power consumption, rotational speed, hour counter, etc. can be read remotely. The commissioning might be more complicated, but once installed, this solution offers more options - especially in terms of integration into BMS systems or smart ventilation systems.
How to set EC fan speed?
Just like fan speed controllers for AC motors, also EC motors can be controlled via an external electrical signal (also called analogue signal) or via Modbus RTU communication. An analogue signal can be generated manually via a potentiometer or automatically via an HVAC sensor. In this way fans with EC motor can be controlled via a potentiometer or via an HVAC sensors.
Following images provides an overview of the possibilities to control an AC motor or an EC motor:
More details can be found on our website - solutions - how to control a fan?
A modern ventilation system works completely autonomously. The most important parameters are continuously monitored in a discreet manner. Additional fresh air is supplied if one of the parameters deviates. No interaction from the residents is required for the proper functioning of the ventilation system. The system only provides an indication when maintenance is required.
However, not every room in a building is used for the same purpose. Depending on the way a room is used, ventilation will have to be controlled differently. In this article we would like to discuss some typical situations for optimally controlling a ventilation system. The choice of sensor type is usually determined by the circumstances.
However, not every room in a building is used for the same purpose. Depending on the way a room is used, ventilation will have to be controlled differently. In this article we would like to discuss some typical situations for optimally controlling a ventilation system. The choice of sensor type is usually determined by the circumstances.
CO2 sensors for spaces with variable occupancy
Indoor carbon dioxide concentrations are the result of a combination of outdoor CO2, indoor breathing and the ventilation rate of the building. When people breathe, they release CO2 into the air. If there's too much CO2, extra fresh air must be supplied to reduce the CO2 level. As buildings and homes become more energy-efficient and thus airtight, this means we have less fresh air coming naturally into the building. Many of today’s ventilation systems recycle air to conserve energy, thus pushing contaminated air back into the building rather than cycling in new fresh air. This results in high CO2 concentrations and poor indoor air quality. Air flow should be monitored to ensure fresh air is supplied in due time.
Indoor carbon dioxide concentrations are the result of a combination of outdoor CO2, indoor breathing and the ventilation rate of the building. When people breathe, they release CO2 into the air. If there's too much CO2, extra fresh air must be supplied to reduce the CO2 level. As buildings and homes become more energy-efficient and thus airtight, this means we have less fresh air coming naturally into the building. Many of today’s ventilation systems recycle air to conserve energy, thus pushing contaminated air back into the building rather than cycling in new fresh air. This results in high CO2 concentrations and poor indoor air quality. Air flow should be monitored to ensure fresh air is supplied in due time.
Moderate to high levels of carbon dioxide can cause headaches, reduced concentration and fatigue while higher concentrations can even produce nausea, dizziness and vomiting. Indoor CO2 levels constantly change, depending on the ventilation, the amount of people and the length of time they are present in an enclosed space. Indoor CO2 levels between 450 - 1.000 ppm are acceptable. When the values exceed this range, additional ventilation is required. Sentera CO2 sensors accurately measure the CO2 levels in the ambient air. They are available in different enclosure types, depending on the application.
In areas with variable occupancy such as meeting rooms, auditoriums or other rooms where many people periodically come together, there will be strong fluctuations in CO2 concentration. Also in a living room or bedroom CO2 sensors are the best choice to control a ventilation system and optimize the supply of fresh air. The CO2 concentration must be measured in the extracted air. In residential environment, room or duct CO2 sensors usually used for this application. In general we can assume that the CO2 level of the supplied air is quite constant and in all cases is lower than the CO2 level of the indoor air. Other parameters such as relative humidity and VOC concentrations usually remain more stable in these spaces.
concentration. Also in a living room or bedroom CO2 sensors are the best choice to control a ventilation system and optimize the supply of fresh air. The CO2 concentration must be measured in the extracted air. In residential environment, room or duct CO2 sensors usually used for this application. In general we can assume that the CO2 level of the supplied air is quite constant and in all cases is lower than the CO2 level of the indoor air. Other parameters such as relative humidity and VOC concentrations usually remain more stable in these spaces. If the rooms in the building are equipped with control valves to regulate the amount of supplied air and the amount of extracted air, the exhaust valve should be controlled by a CO2 controller in the room. The supply valve should follow the position of the exhaust valve to avoid over pressure or under pressure in the room (balanced ventilation). If there is only one central exhaust fan or one heat recovery unit, it can be directly controlled by the CO2 controller. Another option is to install multiple sensors and to control ventilation based on the highest CO2 measurement in the building. For this purpose, Sentera developed the solution FS-D-000064.
To control the ventilation system not only on the basis of the CO2 measurement, but on the basis of both CO2 and relative humidity (and possibly also temperature), a CO2 controller must be used. This device has a built-in control algorithm that can control a valve or fan speed. All (or some) of the measured values will be taken into account by the algorithm.
A CO2 sensor converts the measured CO2 value as well as the relative humidity (and temperature) into three separate analog signals. A valve position or fan speed can be controlled with one of these signals. Not with all three at the same time.
Prevent condensation in wet rooms
Spaces such as toilets, bathrooms or kitchens have greater variations in relative humidity. Relative humidity indicates the actual water content of air as a percentage of the maximum amount it could possibly hold at its current temperature. Warm air can possess more water moisture than cold air, so with the same amount of absolute/specific humidity, the relative humidity of cold air would be far higher than of warm air. Other parameters such as CO2 or VOC generally remain more constant here. It therefore makes more sense to ventilate these areas in such a way that the risk of condensation is minimized. Condensation or excessive humidity can lead to mold and mildew, which isn't good for anyone's health.
Controlling the ventilation system based on the relative humidity in the room itself is not effective. The relative humidity of the supplied air will also not be constant. When controlling the ventilation system based on CO2, it can be assumed that the CO2 concentration of fresh outside air is fairly constant. That is not the case with relative humidity. The relative humidity outside on a warm summer day or a wet autumn day will be completely different. Regulating a ventilation system only on the relative humidity measurement inside, doesn’t work.
Based on the temperature and relative humidity measurements, the dew point temperature can be calculated. Sentera relative humidity sensors measure both temperature and relative humidity and automatically calculate the dew point temperature. When the air comes into contact with an object that has a temperature lower than the dew point temperature, condensation occurs. So, the dew point temperature of the supplied air must always be lower than the temperature inside the wet room. When we obtain this, we can avoid condensation.
So when the relative humidity in a wet room is too high, this can be solved by ventilation if the dew point temperature of the supplied air is sufficiently low. This requires a relative humidity sensor in the interior space as well as a dew point temperature calculation of the supplied air.
VOC sensors in rooms with specific destinations
Then there are also the spaces where VOC sensors are best to assess the indoor air used and control the ventilation system. VOCs or Volatile Organic Compounds are a large group of chemicals that are found in plenty of products we use to build and maintain our homes and buildings. Common examples of VOCs that are present in our daily lives are: benzene, xylene, ethylene glycol, formaldehyde and methylene chloride. Typical sources are paints or varnishes, new carpets, adhesives, cleaning products, dry cleaning, photocopiers and building materials like foam. Also cigarettes and burning of wood emits VOCs. The risk of health issues from inhaling any chemical depends on the exact chemical compound, the concentration and the duration of the exposure.
Breathing in low levels of VOCs for a longer period in time may increase some people’s risk of health problems, especially persons with asthma or particularly sensitive to chemicals. Since VOCs refer to a group of chemicals, each of them has its own toxicity and potential for causing different health effects. In general, breathing in high levels of VOCs is known to cause eye, nose and throat irritations, headaches, drowsiness, nausea, reduced concentration and fatigue. In the long run it can lead to cancer and damage to the liver, kidney and the central nervous system.
Controlling a ventilation system based on a VOC measurement of the extracted air is recommended in areas such as: storage rooms, room where the copy machine is located, printing companies, warehouses for building materials, etc. VOC sensors are usually used where controlling ventilation based on CO2 measurement or humidity is not an option.
If the rooms in the building are equipped with control valves to regulate the amount of supplied air and the amount of extracted air, the exhaust valve should be controlled by a VOC controller in the room. The supply valve should follow the position of the exhaust valve to avoid over pressure or under pressure in the room (balanced ventilation). If there is only one central exhaust fan or one heat recovery unit, it can be directly controlled by the VOC controller.
Efficiently operating differential pressure sensors, controllers and switches are essential for achieving good air quality that every reliable HVAC system should create. Effective ventilation relies on maintaining the correct level of differential pressure throughout the system. Insufficient pressure differentials can lead to issues such as inadequate airflow, which compromises indoor air quality and comfort. Conversely, excessive differentials may strain components and increase energy consumption.
The term "differential pressure" denotes the pressure variance between two distinct locations. Various industries utilise differential pressure sensors to gauge this particular form of pressure.
What is a differential pressure switch?
Differential pressure switches detect disparities in pressure between these two specified points. These switches feature two ports linked to the respective pressure sources, thereby monitoring the differential pressure between them. Upon reaching a predefined threshold, the internal diaphragm within the switch deflects to establish or interrupt a circuit connection. This alteration in the circuit triggers an alarm, notifying users of the pressure shift. Users can either preset the switching point or adjust it on-site.
Differential pressure switches detect disparities in pressure between these two specified points. These switches feature two ports linked to the respective pressure sources, thereby monitoring the differential pressure between them. Upon reaching a predefined threshold, the internal diaphragm within the switch deflects to establish or interrupt a circuit connection. This alteration in the circuit triggers an alarm, notifying users of the pressure shift. Users can either preset the switching point or adjust it on-site.
What is a differential pressure sensor?
Differential pressure sensors, also known as transmitters or transducers, are devices designed to measure the disparity between two absolute pressures. They can be used for filter monitoring, cleanroom ventilation, etc.
The operational principle of a differential pressure transducer involves two hermetically sealed chambers, each equipped with a process connection. These chambers are separated by a flexible membrane, affixed with a resistance bridge. The process connections are positioned before and after any potential pressure reduction, ensuring that the pressures exert opposite forces on the membrane.
Under equal pressure conditions in both chambers, the membrane remains flat. However, when there is a variation in pressure within one of the chambers, the membrane deflects towards the chamber with the lower pressure. The extent of this deformation corresponds to the difference between the two pressures. This deformation induces a change in the resistance value of the bridge, which can then be converted into an electrical signal (transmitted by the sensor analogue output) for subsequent processing by an EC fan or AC fan speed controller.
Differential pressure sensors, also known as transmitters or transducers, are devices designed to measure the disparity between two absolute pressures. They can be used for filter monitoring, cleanroom ventilation, etc.
The operational principle of a differential pressure transducer involves two hermetically sealed chambers, each equipped with a process connection. These chambers are separated by a flexible membrane, affixed with a resistance bridge. The process connections are positioned before and after any potential pressure reduction, ensuring that the pressures exert opposite forces on the membrane.
Under equal pressure conditions in both chambers, the membrane remains flat. However, when there is a variation in pressure within one of the chambers, the membrane deflects towards the chamber with the lower pressure. The extent of this deformation corresponds to the difference between the two pressures. This deformation induces a change in the resistance value of the bridge, which can then be converted into an electrical signal (transmitted by the sensor analogue output) for subsequent processing by an EC fan or AC fan speed controller.
There are two primary methods of measurement for Sentera’s low-resolution sensor types: piezoresistive and capacitive. The majority of differential pressure sensors utilize the piezoresistive effect, wherein the electrical resistance of a material changes under tension or pressure. All piezoresistive sensors exhibit minimal drift. On the other hand, capacitive transmitters for differential pressure feature a capacitor embedded within a silicon chip. Changes in capacitance provide insights into the resulting pressure difference.
Sentera’s most recent high-resolution sensor series feature a digital, low pressure MEMS sensor element (micro-electromechanical system) offering state-of-the-art pressure transducer technology and CMOS (complementary metal–oxide–semiconductor) mixed signal processing technology to produce a digital, fully conditioned, multi-order pressure and temperature compensated sensor with a dual vertical porting option.
Sentera’s most recent high-resolution sensor series feature a digital, low pressure MEMS sensor element (micro-electromechanical system) offering state-of-the-art pressure transducer technology and CMOS (complementary metal–oxide–semiconductor) mixed signal processing technology to produce a digital, fully conditioned, multi-order pressure and temperature compensated sensor with a dual vertical porting option.
What is a differential pressure controller?
A sensor controller offers the possibility to define a setpoint for a single parameter. This setpoint is the greatest difference between this type of devices and the others. Instead of a range of values, only one point is acceptable for the sensor controller. This category contains only the Sentera's sensor controllers that measure differential pressure, volume flow and air velocity. It is a separate category because it does not have a proportional output, but a PI algorithm. PI stands for Proportional Integral. It is a control loop that continually calculates a correction between a setpoint and the actual measurement.
The PI algorithm controls the analogue output. The PI algorithm ensures that the controlled parameter retains its setpoint value.
For example: the differential pressure controller controls the 0-10 Volt output to maintain the differential pressure at the requested setpoint.
Sentera’s differential pressure sensors, switches and controllers are used to measure and control low differential pressures of non-aggressive and non-combustible gases, but they have been especially developed for air. The selectable analogue / modulating output signal has different meaning, depending on the setting of the device. If the device is used as a pressure sensor, the output signal is proportional to the measured pressure. As a volume flow sensor, the device calculates the process flow using differential pressure readings. In air velocity control, the output signal represents a manipulated variable of the PI control.
Depending on the connected differential pressure accessories, the devices can measure and/or monitor and control different parameters. Based on this measurement, air volume flow [m³/h] or air velocity [m/s] can be calculated. To calculate air volume flow based on the K-factor of the fan, use the connection set type PSET-PVC-200 or PSET-QF-200. This optional connection set can also be used to measure differential pressure. To calculate air volume flow based on the duct cross section [cm²] or air velocity [m/s], use the optional connection set type PSET-PTS-200 or PSET-PTL-200.
What is an air filter monitoring device? An air filter monitoring device is a piece of equipment used in HVAC systems to monitor the condition and efficiency of air filters. These devices typically employ sensors or detectors to assess factors such as airflow, pressure differentials, particle concentration, or filter resistance. By continuously monitoring these parameters, the device can indicate when filters need replacement or maintenance. This helps ensure that air filters are changed at the appropriate intervals, maximizing system performance, indoor air quality, and energy efficiency.
Sentera’s FIM series of filter monitoring devices, offers options to monitor either one or two air filters simultaneously. The series can be used for monitoring pressure drops. Air filters impede airflow, creating resistance. As dust and particles accumulate, this resistance increases, causing a higher pressure drop across the filter. The monitoring device measures this pressure drop, indicating filter condition. If it surpasses a set threshold, it signals the need for maintenance.
Also, the FIM series can send real-time data and alerts, allowing continuous monitoring by operators or maintenance staff. Notifications or alarms are triggered when filters require attention, facilitating prompt maintenance actions. Alerts are delivered via SMS or email.
These devices record and store data on filter performance, pressure drop trends, and other relevant parameters. Analysis of this data enables identification of patterns, optimization of maintenance schedules, and detection of potential filtration system issues.
What is more, to facilitate the last two features, the FIM can be connected to SenteraWeb, our online HVAC portal, thanks to the integrated Sentera Internet Gateway.
Significance of differential pressure sensing devices
Differential pressure measuring and controlling devices are integral to HVAC systems for assessing flow rates and pressures within air ducts and enclosed spaces. They facilitate the efficient and cost-effective operation of the systems. Pressure sensors serve as the cornerstone for HVAC system regulation, particularly crucial amid evolving stringent regulatory standards to ensure minimal energy consumption.
Moreover, differential pressure sensors contribute to enhanced comfort and, in certain scenarios, heightened safety within environments by monitoring key HVAC system parameters.
Key monitoring elements in HVAC Systems
Volume: Differential pressure sensors regulate air volume flow, enabling precise control over damper positions and facilitating demand-controlled ventilation.
Duct Pressure: Differential pressure sensors monitor pressure differentials in ventilation ducts, allowing for modulation of fan power to maintain consistent airflow.
Room Pressure: In addition to maintaining uniform pressure levels within standard air-conditioned spaces, differential pressure sensors are vital for specialized environments like cleanrooms, hospitals and laboratories to ensure appropriate pressure differentials for contamination control.
Filter Maintenance: Differential pressure sensors monitor filter condition by detecting pressure drops, prompting timely replacement notifications and even identifying torn filters.
What is stratification and destratification?
In buildings with high ceilings warm air, being lighter, rises to the ceiling, leaving denser, colder air at the floor level causing temperature disparities. This phenomenon is called thermal stratification and it can become a significant concern. This natural process leads to considerable temperature differences within the space. Stratification not only drives up energy bills but also it can be a potential strain on your heating systems and compromises occupant comfort. The solution lies in strategically implementing destratification fans, which effectively combat this energy-guzzling phenomenon. Destratification consists in bringing the layer of warm air that is near the ceiling back down. Thanks to this, the thermal energy in the room is redistributed evenly.
How does the destratification process work?
Destratification is the active approach to counteracting the effects of stratification. It is a process of continuously circulating air from the ceiling to the floor, breaking up the layers of stratified air. Destratification is achieved by using ceiling fans that bring the warm air back down. This dynamic air movement balances temperature differentials, creating a more comfortable environment without the need for excessive heating or cooling. By eliminating thermal layers, these fans contribute to improved air circulation, customer satisfaction, and heightened employee productivity. The reduction in temperature differences between ceiling and floor levels not only enhances comfort but also reduces strain on your heating system and leads to substantial energy savings.
Key benefits of destratification
Balancing temperatures: Constant air mixing is used to regulate room temperature, ensuring a consistently comfortable environment.
Energy and cost savings: Destratification can significantly reduce heating and cooling costs. When warm air is evenly distributed, thermostats can be set to lower values during winter and higher values during summer without negatively affecting room comfort. This leads to less energy consumption and lower electricity and gas bills.
Reduces strain on your heating system: By balancing temperatures through air mixing, a more consistent temperature in the space is achieved. When heating and cooling systems do not have to work as intensively, there is less wear and tear on these devices. This can extend their lifespan and reduce maintenance and repair costs.
Improved room comfort: By equalizing air temperature, destratification fans reduce costs and enhance overall comfort levels in buildings. In this way, building occupants do not have to deal with unpleasant temperature differences, which can improve their productivity and well-being.
How to control ceiling fans?
Now that we've explained how destratification works, let's take a look at how it can be applied in practice. Effective air destratification uses different components and strategies. A key element of this process are special fans designed to circulate the air, known as destratification or ceiling fans. These fans are strategically placed in the space to disrupt the natural stratification of air, redistribute warm air from the ceiling downwards, and improve overall air circulation.
In addition to fans, control systems are necessary to optimize destratification. At Sentera, we offer advanced control solutions designed specifically for this purpose. Our controllers automatically turn on fans based on temperature differences or pre-set times. Setting up these controllers is simple – once you place the sensors (one near the floor and one near the ceiling) and connect them to our destratification controller, you're almost done. The last step is to connect the destratification fan to this controller and configure it.
These systems can adjust the fan speed to meet the specific needs of a given space, ensuring optimal air movement. Another important aspect of maintaining air quality is proper ventilation to prevent stagnation. Factors such as building design, ceiling height, layout, and insulation affect the effectiveness of destratification measures. These factors determine the location and size of destratification fans and influence air circulation patterns.
Regular maintenance is essential to ensure the longevity and efficiency of your destratification equipment. This includes regular cleaning, lubrication, and inspection of fans and controls. Monitoring air quality and temperature levels can help detect any deficiencies or problems and encourage timely maintenance. While HVAC systems typically require maintenance twice a year, air quality monitoring can signal when maintenance is needed, ensuring optimal system performance.
Where is destratification used?
Destratification is effective not only in large commercial and industrial buildings but also in smaller spaces such as schools, offices, and homes. Investments in destratification fans often pay for themselves within a few years due to energy savings and lower maintenance costs.
- Industrial buildings: The high ceilings and large spaces of industrial buildings are ideal for destratification. Even distribution of heat can significantly reduce energy costs.
- Offices and commercial spaces: In offices and commercial spaces, destratification can improve employee and customer comfort, leading to increased productivity and satisfaction.
- Residential properties: In homes with high ceilings or multiple floors, destratification can help maintain a stable temperature and reduce heating and cooling costs.
Energy savings
As a powerful tool in the quest for energy efficiency, destratification fans play a pivotal role during both heating and cooling seasons. They effectively redistribute warm air and reduce energy consumption. For buildings with high ceilings, the benefits are particularly pronounced, making these fans a smart investment for long-term energy savings.
Destratification solutions
Sentera has developed both EC and AC fan speed controllers, the ECMF8 series for EC fans and the TCMF8 series for AC fans. Both series require application specific firmware to operate, which can be downloaded via SenteraWeb. Depending on the controller version, a separate internet gateway may or may not be required. Once the software has been downloaded, it can work stand alone or it can stay connected to SenteraWeb.
By creating and incorporating your own installation into this cloud platform, you can enjoy benefits such as:
- Easy remote monitoring or changing parameters and settings of connected devices
- Data logging: Create diagrams and export data, such as visualisation and recording of ceiling and floor temperatures
- Creating different regimes for your ventilation system, for example day-night regime.
- Receiving alerts or warnings when measured values exceed warning ranges or when errors or abnormalities occur
- Defining users and allowing them to log in to monitor the installation via a standard web browser
For easier installation Sentera offers complete packages that have everything you need for a specific function, we call them solutions. Check out also all of the other solutions that we have in the Solutions tab.
In conclusion, the use of destratification fans emerges as a multifaceted solution, addressing not only energy efficiency but also indoor air quality and overall occupant well-being. As buildings face unique climate challenges, the integration of destratification fans stands out as a strategic and sustainable choice for optimizing HVAC systems.
With spring already here and summer fast approaching, maintaining a lush, vibrant lawn is quickly climbing the priority list for a lot of homeowners. A well-maintained lawn is more than just a pretty sight - it provides a soft, safe area for outdoor activities and can even improve your home's market value. From an environmental perspective, lawns help control erosion, reduce surface runoff, and improve air quality by trapping dust and other particles. However, achieving and maintaining a healthy lawn comes with its challenges. Overwatering can lead to waterlogged soil, promoting fungal diseases and root rot, while underwatering can stress the grass, making it more susceptible to pests and weeds. Inefficient watering practices, such as watering during the hottest part of the day, can lead to rapid evaporation and water waste. Addressing these challenges requires a precise and informed approach to lawn care, which is where moisture sensors come in.
Moisture sensors are devices designed to measure the moisture content in your soil accurately. These sensors come in various types, from simple soil moisture probes that provide basic readings to sophisticated digital sensors that offer detailed data and integration with smart irrigation systems. By installing moisture sensors in your lawn, you can obtain real-time information about the soil's moisture levels, enabling you to water your lawn only when necessary and avoid the pitfalls of overwatering or underwatering. Maintaining optimal soil moisture is crucial for the health of your lawn - moisture sensors help ensure that your grass receives the right amount of water, promoting strong root growth and reducing the risk of diseases that thrive in overly wet conditions. A well-hydrated lawn is also more resilient to stress from heat and foot traffic, leading to a lush, green appearance year-round.
Outside of making lawn-care easier, one of the most significant benefits of using moisture sensors is water conservation. Traditional watering methods often lead to overuse of water, either due to a lack of information about soil moisture or inefficient watering schedules. Moisture sensors ensure that water is used efficiently by providing accurate data on when and how much to water. This can result in substantial water savings, especially in regions prone to drought or where water is a limited resource. By preventing overwatering and reducing water usage, moisture sensors can lead to significant cost savings on your water bill. Additionally, a healthier lawn requires fewer inputs such as fertilizers, pesticides, and herbicides, further reducing your lawn care expenses. Over time, the investment in moisture sensors can pay for itself through these savings. Using water more efficiently has a positive impact on the environment as well. Reduced water usage means less strain on local water supplies and less energy required for water treatment and distribution. Moreover, healthy lawns contribute to local ecosystems by providing habitats for insects and small wildlife, improving soil health, and enhancing the overall green space in urban areas.
How Do Moisture Sensors Work?
There are several different ways to measure soil humidity. Our SWCSM-075 sensors are capacitance sensors - they consist of two electrodes forming a capacitor with the soil acting as the dielectric medium. A capacitance sensor offers a great combination of portability, accuracy and measuring speed. Installing capacitance moisture sensors is a straightforward process that can be done by any homeowner. The sensors are typically buried at various points in your lawn to get an accurate reading of soil moisture across different areas by measuring the capacity changes of the PCB board. It’s essential to install the sensors at the root level of your grass, completely covered by soil and away from any metal objects (such as metal poles or stakes) to ensure accurate measurements. Once installed, moisture sensors can be queried at any time for the soil moisture levels and send this data to a central controller that can utilize Modbus or to your SenteraWeb account via an internet gateway. Advanced systems can automatically adjust your irrigation schedule based on the sensor readings, ensuring your lawn receives the right amount of water at the right time. This automation takes the guesswork out of lawn care and provides peace of mind that your lawn is being properly cared for - almost like having a personal gardener. The data collected by moisture sensors can be used to fine-tune your watering practices. Many systems offer user-friendly interfaces that display moisture levels, historical data, and watering recommendations. By analyzing this data, homeowners can make informed decisions about their lawn care, such as adjusting watering frequency during dry spells or reducing water usage during rainy periods.
There are several different ways to measure soil humidity. Our SWCSM-075 sensors are capacitance sensors - they consist of two electrodes forming a capacitor with the soil acting as the dielectric medium. A capacitance sensor offers a great combination of portability, accuracy and measuring speed. Installing capacitance moisture sensors is a straightforward process that can be done by any homeowner. The sensors are typically buried at various points in your lawn to get an accurate reading of soil moisture across different areas by measuring the capacity changes of the PCB board. It’s essential to install the sensors at the root level of your grass, completely covered by soil and away from any metal objects (such as metal poles or stakes) to ensure accurate measurements. Once installed, moisture sensors can be queried at any time for the soil moisture levels and send this data to a central controller that can utilize Modbus or to your SenteraWeb account via an internet gateway. Advanced systems can automatically adjust your irrigation schedule based on the sensor readings, ensuring your lawn receives the right amount of water at the right time. This automation takes the guesswork out of lawn care and provides peace of mind that your lawn is being properly cared for - almost like having a personal gardener. The data collected by moisture sensors can be used to fine-tune your watering practices. Many systems offer user-friendly interfaces that display moisture levels, historical data, and watering recommendations. By analyzing this data, homeowners can make informed decisions about their lawn care, such as adjusting watering frequency during dry spells or reducing water usage during rainy periods.
When selecting a moisture sensor, it’s important to consider several factors to ensure you choose the right one for your lawn care needs. Ensure the moisture sensor is compatible with your existing irrigation system. Investing in moisture sensors can revolutionize your lawn care routine. By ensuring your lawn gets the right amount of water, you’ll enjoy a greener, healthier lawn while conserving water and saving money. For the best results, combine the use of moisture sensors with seasonal lawn care practices. Adjust your watering schedules according to the changing weather, fertilize your lawn appropriately, and mow at the right height to promote healthy grass growth. By taking a holistic approach to lawn care, you can achieve the lush, green lawn you've always wanted.
To help you along on your journey to a perfect lawn, we offer the SWCSM-075 soil moisture sensor with an integrated 7.5m cable with an M12 connector, as well as a the ADPT-SWCSM adaptor for it, which allows you to connect the sensor to the Sentera PoM network. The adaptor offers 24V DC power supply over Modbus and Modbus RTU communication via a UTP cable with an RJ45 connector. The adaptor also allows you to daisy-chain as many sensors as you need in order to cover the full area you are looking to monitor.
Developed in 1979 by Modicon (now Schneider Electric) for use with their PLCs, Modbus has become a standard for connecting industrial electronic devices. Modbus RTU (Remote Terminal Unit) is one of the most commonly used communication protocols in industrial automation. It is a serial communication method that allows multiple devices to be connected on a single communication line, facilitating efficient data exchange between controllers, sensors, actuators, and other devices.
Key Benefits of Modbus RTU Communication:
- Simplicity and Ease of Implementation - Modbus RTU communication uses a simple, easy-to-understand protocol structure that allows for rapid integration and minimal troubleshooting. The protocol is straightforward, reducing the learning curve for engineers and technicians.
- Flexibility and Scalability - Modbus RTU network allows up to 247 devices to communicate on the same network without the need for complex configurations. It can be expanded easily to include more devices or upgraded to support newer Modbus standards.
- Interoperability - As an open protocol, Modbus RTU ensures interoperability across a wide range of devices and software applications. As an open standard, Modbus RTU ensures that most devices from different manufacturers can communicate seamlessly.
- Robustness and Reliability - Modbus RTU communication uses Cyclic Redundancy Check (CRC) for error detection, ensuring reliable data transmission. It is designed to be resistant to electrical noise, making it suitable for harsh industrial environments.
- Versatility - Modbus RTU communication is applicable in various sectors including manufacturing, building automation, energy management, HVAC and more. It can be used with PLCs, HMIs, sensors, actuators, and other industrial devices.
- Simultaneous Reading of Multiple Parameters - Modbus RTU communication is capable of polling multiple data points from a single device in one communication cycle. It facilitates comprehensive data collection and monitoring by central systems, enabling efficient handling of multiple parameters.
Modbus - a robust and interference-resistant communication
Modbus communication was developed to allow multiple devices (e.g. sensors, fan speed controllers and logic controllers) to work together reliably in an industrial environment. Also in a building there is a great risk of interference for classic analogue (0-10 Volt) signals, especially in the case of long cables that are located in the vicinity of power cables. Modbus communication is much more stable and reliable compared to analogue signals. It offers the possibility to use significantly longer cable lengths without the risk of disruptions or data loss. When working with analogue signals, the cable lengths must be kept shorter to prevent interference.
In addition to the possibility of using longer cable lengths, Modbus RTU communication also offers the following advantages compared to analog signals:
- Precision and Accuracy - Modbus communication, being digital, provides high precision and accuracy in data transmission. Unlike analogue signals, which can suffer from signal degradation and noise interference over long distances, Modbus transmits data in a digital format, ensuring that the information remains intact and accurate. To reduce the risk of interferences, analogue signal cables are usually installed in a separate cable tray. Physically separated from power lines.
- Data Richness - Digital communication via Modbus allows for the transmission of more complex and detailed data. While analogue signals typically convey a single measurement (e.g., temperature or pressure), Modbus can transmit multiple parameters and status information simultaneously. This includes diagnostics, configuration settings, and multiple sensor readings, enabling more comprehensive monitoring and control. When controlling an EC motor via a 0-10 Volt signal, we know what the desired fan speed is. What the fan does in practice and whether it runs at all is uncertain. If we control the same EC fan via Modbus communication, we can also request feedback from the fan. For example, we can read the effective fan speed, monitor the temperature of the EC motor, monitor the power consumption, receive notifications if a motor problem occurs, etc.
- Interoperability - Modbus is an open and widely adopted protocol, meaning it is supported by a vast array of devices from different manufacturers. This interoperability ensures that components can easily communicate with each other, facilitating integration and reducing dependency on specific vendors. In contrast, analogue systems often face compatibility issues when integrating devices from different manufacturers. With a 0-10 Volt signal, attention must be paid to whether or not the ground signals may be linked together. In some cases there is a risk of short circuit. With PWM signals, both devices must use the same frequency, the amplitude of the PWM signal must be correct, etc. Usually only one (or a limited number of devices) can use one analog signal.
- Ease of Troubleshooting and Maintenance - Digital systems like Modbus offer enhanced diagnostic capabilities, using Cyclic Redundancy Check (CRC). It provides detailed error messages and status reports, making it easier to identify and resolve issues. When connected to the cloud, remote diagnostics are an option too. Analogue systems typically require on-site manual inspection and testing to diagnose problems, which can be time-consuming and less precise.
- Flexibility and Functionality - Modbus allows for bi-directional communication, enabling not only the collection of data but also the sending of commands to field devices. This capability supports advanced control strategies and automation tasks that are not feasible with unidirectional analogue signals.
- Reduced Signal Wiring - Modbus communication reduces the need for extensive signal wiring. Instead of running individual wires with proper shielding and grounding for each analogue signal, a single digital communication line can carry multiple signals. This simplifies the installation process, reduces potential points of failure, and lowers material and labor costs.
- Scalability - Modbus supports the connection of multiple devices on the same network, allowing for easy scalability. Adding more sensors or devices does not require significant changes to the wiring or infrastructure, as would be the case with analogue systems, where scalability is limited by the number of available I/O points. This flexibility is essential in modern industrial environments where systems need to adapt to changing requirements.
Thanks to the RS485 technology, Modbus is a robust and interference-resistant communication. Therefore, Modbus communication is a widely used standard, both in industrial and in HVAC applications. Since it is an open protocol, devices from different manufacturers can exchange information with each other via Modbus communication. It can be seen as a universal language. Sentera products also exchange information via Modbus communication. This makes it possible to make them work together in a simple way. Adjusting settings of Sentera devices can also be done easily via Modbus communication.
While Modbus communication offers significant advantages, it is not universally applicable. There are specific situations where digital or analogue signals are preferable or necessary. Legacy and simple HVAC equipment was designed before the adoption of Modbus and only support analogue or digital signals. For these cases, Sentera offers a wide range of converters. Their primary function is to gather data from analogue sensors or digital switches, convert it into the appropriate Modbus RTU format, and then transmit it to a HVAC controller or BMS. This ensures communication and interoperability between devices that otherwise would not be compatible with the Modbus protocol.
In summary, Modbus communication offers significant advantages over analogue signals, including higher precision, scalability, richer data transmission, interoperability, ease of troubleshooting, long-distance communication capabilities, cost-effectiveness, enhanced functionality, security, and reduced wiring complexity. These benefits make Modbus a preferred choice for modern industrial and home and building automation applications, contributing to more efficient, reliable, and flexible control systems.
In scientific terms, clean air refers to a specific combination of components such as nitrogen (N2), oxygen (O2), argon (Ar), carbon dioxide (CO2) and water vapour. Their quantity can differ depending on the location and specific environmental conditions. However, air contains gases with variable concentrations also known as air pollutants. There are six major air pollutants that are set as criteria by the Federation of European Heating, Ventilation and Air Conditioning Association (REHVA). They should be found in specific quantities based on the criteria established by WHO (World Health Organisation) for air to be considered clean.
Where does the problem lie?
There are plenty of medical conditions that come as a result of inhalation of air that contains high levels of air pollutants. Therefore, it is important that outdoor and indoor spaces are equipped with sensors that can detect the levels of air pollutants and guarantee air quality. Although it is difficult to maintain air quality that is entirely void of air pollutants, low levels of air pollution guarantee human safety.
Nowadays, life has become so fast-paced that people need to juggle their career, personal and social life. This is exactly when they are the most prone to forgetting about the environmental factors that play a key role in everyday life. For instance, a long day spent at the office with high levels of CO2 can result in unpleasant medical conditions such as headaches, fatigue and muscle twitches. In order for human beings to live their lives healthily, air quality should be of high priority.
Main Air Pollutants
To understand better air quality, it is important for one to be informed of the types of air pollutants, their sources, the chemical reactions they take part in and their impact on human health.
1. Particulate matter (PM) refers to a mixture of solids or liquid droplets that are found in air. They vary in terms of size, chemical composition and shape. The particles that are 10 micrometres (PM10) or less and 2.5 micrometres (PM2.5) or less in diameter are considered dangerous since they can be inhaled and they can enter your lungs, negatively affecting your respiratory system. Additionally, some of them can even go into your bloodstream.
Particles can also form acid rain that harms the environment and damages buildings and monuments. Another example of the presence of PM2.5 and PM10 in air is the formation of haze in cities. Haze leads to reduced visibility, which can result in traffic accidents since drivers are unable to see obstacles, pedestrians and other moving vehicles.
Some of the main sources of PM2.5 and PM10 are power plants and automobiles which emit chemicals such as sulphur dioxide and nitrogen oxides that are a result of complex chemical reactions. Additionally, particles are directly emitted by construction sites, fields, unpaved roads and fires. Some of the sources can be found indoors and can include activities such as smoking, cooking on a woodstove, burning food when cooking, lighting candles and fireplaces. Dust and pollen, which can enter indoor areas through open windows, are also regarded as a source of PM2.5 and PM10.
2. Ozone (O3) is another air pollutant that is formed due to complex chemical reactions in the atmosphere. The major components responsible for the formation of ozone (O3) in polluted atmosphere are nitrogen (N2) and volatile organic compounds (VOCs).
The main sources of nitrogen oxides (Nox) and volatile organic compounds (VOCs) are the emissions form cars, power plans, chemical plants, electric utilities, gasoline vapours and refineries which react in the presence of sunlight creating ozone (O3). Ozone (O3) is most commonly found in urban areas, however, it can be spread through long distances by wind resulting in higher levels of pollution in rural areas as well. It is one of the main components of smog, which leads to reduced visibility and air quality.
When breathed in, O3 can cause irritation and inflammation of the respiratory system, resulting in coughing, chest discomfort and increase in asthmatic attacks for the ones suffering from the medical condition. When exposed to high levels of O3 for long periods of time, children, the elderly and individuals with respiratory illnesses are particularly prone to developing reduced lung function. Additionally, O3 can affect adversely nature and vegetation. It reduces plant growth, photosynthesis and biodiversity.
3. Nitrogen dioxide (NO2) belongs to a group of highly reactive gasses called nitrogen oxides (NOx). Nitrogen dioxide (NO2) is formed in combustion processes involving nitrogen and oxygen.
The main factor for the presence of NO2 in air is the burning of fuel. In this sense, emissions from power plants, vehicles, industrial activities and residential heating play a key role in NO2 levels. In addition, enclosed parking garages require proper ventilation since vehicles produce emissions that are hazardous to health. In this case, the detection of CO2 can be used as criteria for the overall safety of the enclosed parking garages since huge amounts of CO2 are emitted in the combustion of fuel. The CO2 sensors of Sentera are specifically designed to detect CO2 levels, ensuring that they are within a safe range. As a result, Sentera outdoor CO2 sensors are a key element of any ventilation system in enclosed parking garages.
Nitrogen dioxide (NO2) has damaging effects on human health. Exposure to high levels of NO2 over short periods can result in irritation and inflammation of the airways in the human respiratory system. As a result, symptoms such as coughing, difficulty breathing and wheezing may occur.
There also exists an environmental effect of NO2. Nitrogen dioxide (NO2) in combination with water, oxygen and other chemicals forms acid rain. Moreover, NO2 reacts with other air pollutants creating smog and damaging air quality.
4. Carbon monoxide (CO) is a colourless, odourless and tasteless toxic gas. It can be freely combined with air and it is a source of fuel. It also burns with a distinguishable violet flame. Levels of carbon monoxide can be both found indoors and outdoors.
violet flame. Levels of carbon monoxide can be both found indoors and outdoors.The main sources of CO indoors are unvented gas or kerosene heaters, leaking chimneys, furnaces and boilers. Additionally, there are activities that can increase the levels of CO indoors such as smoking and cooking on a gas stove. The outdoor sources of CO are vehicles or machinery that are powered by the combustion of fossil fuels. As a result, high levels of CO can be found in attached garages, parking areas and roads.
The effects of CO are hazardous to human health. Low levels of CO can cause fatigue in healthy people and chest pain in people with heart diseases, especially if they are exercising or under stress. The short-term exposure results in reduced oxygen delivery to the heart. Exposure to high levels of CO can lead to dizziness, headaches, confusion, nausea and reduced vision, coordination and brain function. The highest levels of CO are more likely to happen indoors and can be fatal to humans.
In terms of environmental impact, CO can participate in chemical reactions resulting in the creation of ozone (O3), which has a harmful effect on nature and vegetation.
Nowadays, most vehicles are designed to emit more carbon dioxide (CO2) and less carbon monoxide (CO) in the combustion of fuel. In addition, the fact that CO can react with oxygen (O2), resulting in the formation of CO2, demonstrates a direct link between CO and CO2 levels, especially in enclosed parking garages where air quality depends significantly on a proper ventilation system. The outdoor CO2 sensors of Sentera are specifically developed for accurate CO2 measurements, which can guarantee human safety in enclosed parking garages.
5. The other widely used gas by vehicles is LPG. Due to the environmental impact and state policies, the use of diesel powered engines is shrinking and is being replaced by LPG powered engines that are not that harmful to nature. LPG is used to describe two natural gas liquids: propane and butane, or a mix of the two. LPG vapour can cause fainting and choking in poorly ventilated environments.
To provide safe and healthy control of indoor air quality, a continuous gas monitoring system is necessary.
Sentera’s CO2 sensors are suitable for the measurement of air quality in enclosed parking garages. What is more, these multifunctional sensors also measure temperature, relative humidity and ambient light levels. Based on the temperature and humidity measurement, the dew point is calculated. All these values are available via Modbus RTU.
6. Volatile organic compounds (VOCs) refer to a variety of chemicals such as benzene, toluene, ethylbenzene and xylenes that are found both indoors and outdoors as a result of combustion, evaporation and house renovations. Additionally, they participate in the formation of ozone (O3), haze and acid rain, causing damage to the environment. Some of the main sources of VOCs are cleaning supplies, paints and lacquers, pesticides, permanent markers, building materials and furnishings and office equipment such as copiers and printers.
Volatile organic compounds (VOCs) adversely affect human health and can lead to a variety of symptoms such as nose and throat irritation, allergic skin reaction, headaches, loss of coordination, fatigue and dizziness. Some VOCs are proven to be carcinogens. Studies show that VOC levels are higher indoors rather than outdoors. Having this in mind, Sentera’s room TVOC sensors are designed to measure the level of VOCs indoors and detect any crucial changes. Subsequently, more fresh air is supplied in the room, resulting in lower levels of VOCs.
Conclusion
In conclusion, clean air depends on numerous factors, therefore, air quality needs to be constantly monitored, so human safety is ensured, especially in indoor environments. Additionally, public buildings need to follow certain ventilation regulations that guarantee air quality. The regulations present safety levels, which should not be exceeded in order for the air to be considered safe.
Impacts of poorly functioning ventilation system on inhabitants
Poorly functioning ventilation system has a huge impact on human health. In most cases in which the ventilation system cannot extract a huge percentage of most common pollutants like carbon dioxide, volatile organic compounds or airborne pathogens from the rooms, the air is still contaminated. In such situations, inhabitants may feel dizzy, sick and have some negative impacts on their skin like increased dryness, irritation and sensitivity, acne, infections or even allergic reaction due to increased levels of pollen. However, the bad condition of the ventilation system can also reflect on the installed devices and the fan in it. When the system does not work properly, most of the pollutants from the extracted air clog the installed devices and the fan through the connection elements (pipes, nozzles and etc.) as the devices could wear out, overheat, reduce working efficiency, electrical issues would appear or mostly common to reduce the airflow, which still has a huge impact on human health. This is a clear example of how the ventilation system can reflect on the long-term exploitation life of the installed devices and the human health.
Variable fan speed control through an analogue input
In HVAC control systems, the analogue input is typically used with input sensors in order to produce a voltage, current or resistance change in response to an environmental variations or system measurements or sometimes with a control device, such as a potentiometer, providing the needed output signal. The requested fan speed can be set via the analogue input signal. This analogue signal can be between 0 and 10 V or between 0 and 20 mA and in ascending or descending mode, depending on the used version from the EVS, EVSS, MVS, MVSS and TVSS series of fan speed controllers. In ascending mode, the motor will run at low speed when the analogue signal is at its minimum value (0 V), as the motor will run at high speed when the analogue input is maximum (10 V). In descending mode, the operation is inversed: when there is no 0-10 V input signal available, you can connect an external 10 KOhm potentiometer via the integrated 12 VDC power supply. Sentera has developed many convenient solutions for remote control of the fan speed or the air curtain, which are available on our website. Depending on the application and the required devices, you receive a clear vision for remote and automatic regulating of the fan speed, depending on the measured values of temperature, relative humidity or VOCs.
Connect a sensor or a potentiometer for an automatic control of the fan speed
Sensors in control systems often produce analogue signals that vary in voltage, current or resistance based on the measured parameters of temperature, humidity or other crucial for the human health environmental conditions. For instance, a temperature sensor can generate an output voltage signal proportional to the measured temperature values.
Analogue inputs are designed to capture and interpret signals from sensors that monitor environmental variations or specific parameters within the whole ventilation system system. This can include temperature sensors, pressure sensors, light sensors and other.
When we continuously monitor the information, given from the analogue signals from sensors, the control system can make real-time adjustments in order to maintain the desired from the inhabitants conditions or quickly respond to changes in the environment. This is how the ventilation should really work to have a good impact on the health of the human organism.
Various types of sensors, controllers and transmitters with analogue outputs could be connected to devices with analogue input from the variable fan speed controller series of Sentera. The control system uses the signals from these devices to regulate the operation of heating or cooling elements, fans, and other components to maintain a comfortable indoor environment. The analogue input can also be connected to an external potentiometer providing 0-10 V control signal. In this way, a motor can be regulated based on the input information provided by the potentiometer. You can use Sentera’s potentiometer series LTV, MTP and MTV and see our solution examples of connecting variable fan speed controllers and potentiometers, available on our website.
Standalone or Modbus operation mode
The variable fan speed controller series (EVS, EVSS, MVS, MVSS and TVSS) feature two types of operation modes – standalone and via Modbus RTU communication. In standalone mode, there’s no need to connect the fan speed controller to a computer in order to operate with the device. All you have to do is use the integrated dip switches or trimmers to set the desired speed of the fan directly through the device. If the fan speed controller is in Modbus operation mode, you can operate the chosen device using the Sentera’s free software suite 3SM Center. Sentera’s variable fan speed controllers do have an integrated Modbus RTU and we share the common opinion that the Modbus RTU communication still is the easiest way to connect devices and receive information from them.
Trimmers for setting the desired fan speed Sentera’s variable fan speed controllers have an internal minimum speed trimmer built in, intended for setting the minimum speed sufficiently high to prevent motor overheating and buzzing at low speeds. This is a one-time screwdriver adjustment to an exact desired value and with its help you can avoid motor stalling. Apart from Sentera's standard minimum speed trimmer, some of the variable fan speed controllers feature a maximum or maximum speed trimmer. Thanks to it, the maximum speed of the fan can be restricted, irrespective of the potentiometer position. Using the two trimmers, you can set the speed within the desired limits and still save energy saving and extend the motor service life.
Thermal motor protection in case of overheating
Some series of the fan speed controllers offer thermal motor protection (TK monitoring) against eventual motor heating. This option is available only in MVSS, TVSS and EVSS series of variable fan speed controllers. The thermal contacts measure the temperature in the motor windings and when an extreme motor overheating is detected, the TK function will shut down the motor in order to prevent motor damage.
Two types of enclosure, made from high-quality plastic
The plastic enclosures for variable fan speed controllers are designed with sustainability in mind. They offer robust protection for the internal components of fan speed controllers while being lightweight and durable. These enclosures can withstand various environmental conditions without compromising on performance. Additionally, their production process emphasizes energy efficiency and minimal waste generation. The enclosure of the variable fan speed controller series is made of high-quality r-ABS VO (UL94) type plastic, as it offers two types of mounting – DIN rail or surface, depending on the chosen series of the devices. All of the enclosures of the fan speed controller are made with an IP protection rating (IP30 or IP54, depending on the version chosen) against ingress of dirt, dust and moisture.
How does a transformer fan speed controller work
Transformer controllers regulate the speed of fans with AC motors in steps by reducing the motor voltage. This stepped speed control is accomplished by the electrical transformer they employ, hence the name 'transformer controller'. Transformer fan speed controllers are cost-effective and have proven to be very reliable and robust. They can also be used in situations where the power supply is unstable. Transformer speed controllers are typically used to regulate fan speed. Most customers are willing to accept the disadvantage of a slightly lower energy efficiency because the advantage of user-friendliness is more important to them. A transformer speed controller is one of the simplest methods to control the speed of an electric motor. Both connection and commissioning are particularly straightforward.
Quiet motor operation
These types of fan speed controllers are easy to install. They require no configuration and can be used immediately upon connection. Thanks to transformer technology, they generate a motor voltage with a perfect sinusoidal shape, resulting in exceptionally quiet motor operation and an extended service life. More detailed information about transformer technology is provided below. The perfectly sinusoidal motor voltage is the major advantage compared to electronic TRIAC controllers. A TRIAC controller cuts away pieces of the sinusoidal voltage, while a transformer speed controller maintains the sinusoidal shape but reduces it.
Humming noise of the electrical transformer
In a transformer, the alternating current creates a constantly changing magnetic field, causing the iron core to vibrate at a high frequency, which we perceive as a humming noise. These magnetic fields can cause small movements within the transformer itself. Loose coils, laminations (sheets) in the core, or even the transformer's casing can vibrate slightly, causing a humming sound. It is important to note that some humming is normal for transformers. However, an unusually loud hum can indicate a problem, such as loose parts, overloading, or malfunctioning components. Sentera transformers receive a special impregnated coating that reduces electrical noise from the transformers. Because of this humming noise, we recommend always installing the transformer fan speed controller in a technical room where this noise is disturbing.
Regulating fan speed by reducing the motor voltage
Transformer fan speed controllers regulate fan speed by reducing the motor voltage in steps. TRIAC or electronic fan speed controllers also regulate the motor speed by reducing the motor voltage. The difference is that transformer speed controllers do this in steps, while TRIAC controllers do this continuously. Both types of speed controllers are suitable only for voltage-controllable motors. These are electric motors where the speed can be controlled by lowering the supply voltage while the frequency remains constant. Both TRIAC and transformer fan speed controllers can be used in applications where the torque decreases with speed, such as fan speed control. Controlling the speed of fans with AC motors is one of the most common applications of transformer speed controllers. As mentioned above, the biggest advantages of a transformer fan speed controller are its simple operation and cost-effectiveness. No configuration is needed; once everything is connected, the fan can be controlled immediately. The construction, installation and commissioning of a transformer fan speed controller is much simpler than those of more complex speed controllers like frequency inverters, also translating into lower costs.
The transformer reduces the supply voltage referred to as the primary voltage. The reduced voltage that can be used to supply the motor is called the secondary voltage. The secondary voltage is reduced according to the ratio of the number of primary windings versus the number of secondary windings. For example, if the primary winding is twice the size of the secondary winding, the secondary voltage will be half the primary voltage. The principle diagram on the right shows an electrical transformer with only one secondary voltage. The transformers used in speed controllers offer five different secondary voltages. The motor speed is reduced by connecting the motor to one of these voltage taps (secondary voltages). This can be done by turning a knob, by an analogue input signal or by a command sent via Modbus RTU communication. Most Sentera transformer fan speed controllers allow five different motor speeds to be selected. Some models allow further reduction of the lowest speed by internally connecting the cable of the lowest speed to an even lower voltage tap on the transformer. However, this is not permitted for all motor types. If the starting voltage is too low, the motor may not be able to start, which can block the motor with the risk of burning.
The maximum current that the transformer can supply is determined by the thickness of the copper wires in the transformer coil winding. The maximum motor current determines the type of transformer that must be selected. For a motor with higher currents, a transformer with a thicker wire diameter must be selected. The maximum current capacity of the Sentera transformers is clearly shown on the website. The maximum current capacity means: the current consumption of the motor (expressed in Ampere) when the motor is running at full speed. The higher starting current that occurs briefly during motor start-up should not be taken into account. Sentera transformers have a constant wire thickness over the entire winding, guaranteeing better quality of the transformer. Many competitors offer cheaper transformers with variable wire thickness in the coil winding. As a result of the flow of electrical current, the copper wires will heat up. Thinner wires will heat up faster because they have a higher electrical resistance. When the heating becomes too strong, the insulation of the copper wires will melt, causing a short circuit and permanent damage. When this happens, the transformer must be replaced. Excessively high ambient temperatures, frequently restarting the motor or an installation method with insufficient cooling options can also cause this damage.
AutotransformersSentera transformer fan speed controllers are equipped with one or more autotransformers. An autotransformer employs a single winding (coil) that serves as both the primary and secondary winding. Different voltage taps are utilised to achieve varying output voltages. Unlike the autotransformer, the isolation transformer has two separate windings, the primary and secondary, providing electrical isolation between the input and output.
One winding means there is no galvanic separation of the primary winding from the secondary. The coils are connected directly, resulting in not only electromagnetic but also electrical connectivity. These qualities contribute greatly to higher efficiency, as only a part of the power is converted.
The operation of a transformer is based on two basic principles:
- The time-varying electric current in the primary coil creates a time-varying electromagnetic field.
- The electromagnetic field creates an alternating electric current via electromagnetic induction.
The single winding of an autotransformer yields a more compact and lightweight construction compared to conventional dual-winding transformers. This type of transformer is characterised by compact dimensions, high reliability and long service life. It is frequently used in various industries and production processes, as well as for ordinary household purposes when certain physical quantities need to be regulated.
How an electrical transformer works
In this chapter we explain in detail how an electrical transformer works.
A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. Electromagnetic induction produces an electromotive force within a conductor exposed to time-varying magnetic fields. Transformers are used to increase or decrease the alternating voltages in electric power applications.
Alternating current is applied to the primary coil of the transformer. Current flowing through a coil generates a magnetic field. Since the current in the primary coil is alternating (changing direction constantly), the magnetic field also keeps changing its strength and direction. This "dancing" magnetic field is crucial for the next step.
The changing magnetic field acts like an invisible highway for electrical energy. It cuts through both the primary and secondary coils. In the secondary coil, this changing magnetic field creates a phenomenon called electromagnetic induction. This pushes the electrons in the secondary coil to move, generating a current. It works as follows: when the magnetic field around the conductor (secondary coil) changes, it nudges the electrons inside the conductor. This nudge creates a voltage (ElectroMotive Force or EMF) that pushes the electrons to flow in a particular direction, creating an electric current. The direction of the current depends on the direction of the change in the magnetic field, as explained by Lenz's law.
The voltage in the secondary coil depends on two factors:
- Number of windings: The number of windings in each coil. If the secondary coil has more turns than the primary coil, the voltage will be higher. Conversely, fewer windings in the secondary coil will result in a lower voltage.
- Strength of the Magnetic Field: The strength of the changing magnetic field. A stronger magnetic field will induce a larger voltage in the secondary coil.
A transformer speed controller is robust and easy to use. The disadvantage is the lower energy efficiency compared to more complex speed controllers. The efficiency of a transformer is the ratio of its output power to its input power. The lower energy efficiency of a transformer speed controller is due to:
- Hysteresis Loss: When the magnetic field in the core reverses direction (which happens constantly in AC transformers), the material experiences a microscopic rearrangement of its internal structure. This back-and-forth process consumes a small amount of energy, appearing as heat loss.
- Eddy Current Loss: The changing magnetic field also induces small circulating currents within the iron core itself. These eddy currents heat up the core, representing another form of no-load loss.
- I²R Losses: This is the classic Joule heating effect. The current (I) flowing through the resistance (R) of the copper wires in the primary and secondary coils generates heat. As the load current increases, the I²R losses also increase proportionally.
Sentera employs various techniques to minimise these energy losses:
- High-quality core materials: Using grain-oriented silicon steel with low hysteresis losses is crucial. This steel, also called electrical steel, is more expensive than other types of steel but offers better permeability to magnetic fields, resulting in fewer losses.
- Lamination of the core: The core is made of extra thin metal sheets (laminations) to reduce eddy currents. These thin metal plates are perfectly aligned in the Sentera factory, fixed to each other, and then provided with a special impregnated coating. This method is time-consuming but provides a significant increase in energy efficiency.
- Large conductor size: Using thicker wires in the windings reduces their resistance and lowers I²R losses. High-quality copper with a thick diameter has a lower resistance value, limiting losses at higher currents. Sentera transformers have a constant wire thickness over the entire winding, guaranteeing better quality of the transformer.
Why this basic technology remains interesting
Sentera transformer speed controllers are still widely used for fan speed control. Their ease of use, robust construction and attractive price are the main advantages. The fan speed can be adjusted in steps, and even at low speed the motor remains exceptionally quiet. Disadvantages of this technology are the lower energy efficiency and the noise that the speed controller generates. Sentera transformer speed controllers are designed to minimise these disadvantages as much as possible. Especially for fan applications that do not require continuous operation, a transformer speed controller is the perfect choice. Typical applications are extractor hoods, extraction fans, etc.
Product range of Sentera transformer fan speed controllers
Sentera is one of the leading manufacturers of fan speed controllers. For two decades, our transformer fan speed controllers have been the standard in the HVAC world. Quality and user-friendliness has always been our top priority. Due to the great success, many variants were created. As a result, it is not always easy to get an overview of this product range. The most important properties of the different series are briefly summarized below.
Sentera transformer fan speed controllers for single-phase motors with a maximum load up to (and including) 7,5 A have a high-quality plastic enclosure with metal cooling fins. This housing is manufactured in the Sentera plastics factory from flame-retardant ABS plastic. The cooling fin guarantees sufficient heat dissipation for controllers of this capacity. All other transformer fan speed controllers have a solid metal enclosure with sufficient capacity for heat dissipation.
Transformer fan speed controllers with build-in controls
A first group contains transformer fan speed controllers with build-in control switch(es) on the front panel. These speed controllers are easy to install and operate.
- The entry-level The simplest transformer speed controllers have a rotary switch on the front panel that allows manual selection of fan speed. For single-phase 230 Volt motors there are the STR-1 series, for three-phase 230 Volt motors there are the STR-3 series and for three-phase 400 Volt motors there are the STR-4 series. These are the cheapest and simplest 5-step speed controllers in the Sentera range.
- Motor overheating detection For single-phase and three-phase 400 Volt motors, the entry-level models are also available with an additional safety function to detect motor overheating. These are the STRS1 and STRS4 series respectively. Both series are interesting if the motor is equipped with TK temperature sensors (thermal contact) in the motor winding. These TK temperature sensors can be connected to the STRS1 and STRS4 series. If the motor temperature exceeds a critical value, the 5-step speed controller will shut down the motor to prevent permanent damage.
- Emergency button for smoke evacuation For single-phase motors, the entry-level model is also available with an additional emergency button for smoke extraction. When the emergency button is pressed, the fan accelerates immediately towards maximum speed. After reset of the emergency button, the speed controller will function normally again. SER-1 series control single-phase motors.
- Two separate 5-speed selector switches The SC2-1 series offer not one but two speed selector switches on the front panel. They control single-phase motors. One of both rotary switches is activated via a dry contact input (low or high). In many applications, an external time relay, a temperature switch or a differential pressure relay is connected to this dry contact input. In the case of the temperature switch, for example, the fan is controlled by switch 1 at low temperatures and by switch 2 at higher temperatures. This makes it possible to automatically switch between two different ventilation regimes, depending on the circumstances. It’s a simplified version of demand based ventilation.
- Kitchen hood exhaust fan speed controllers SFPR1 and SFPR4 series are transformer fan speed controllers with an output to control a gas valve. An optional air flow sensor or pressure relay is required to detect the airflow. The output is activated simultaneously with the fan. In case air flow is not detected within 60 seconds after the motor is started, the gas valve output is deactivated. SFPR1 and SFPR4 series control single-phase or three-phase 400 Volt motors respectively. They restart automatically after a power failure and they feature motor overheating detection (TK motor contacts).
Remotely controllable transformer fan speed controllers
In some circumstances it is not desirable for the fan to operate continuously or not at the same speed continuously. Therefore, we offer transformer fan speed controllers that can be controlled remotely. There are variants where only the start signal can be given remotely as well as variants where the speed can be selected remotely.
Transformer fan speed controllers with dry contact inputs
Dry contact inputs can be activated by a digital signal (high or low). Typically, dry contact inputs are activated manually by use of a switch. They can also be activated automatically by use of a timer, a pressure relay, temperature switch, humidity switch, etc…
- STRA1 and STRA4 series feature several additional dry contact inputs to start the motor remotely. The fact that different conditions can be combined makes these controllers universally applicable. The fan speed must be selected via the rotary switch on the front panel. STRA1 and STRA4 series control single-phase or three-phase 400 Volt motors respectively. They restart automatically after a power failure and they feature an alarm output and motor overheating detection (TK motor contacts).
- SC2A1 and SC2A4 series have two speed selector switches on the front panel. These series also offer multiple additional dry contact inputs to start the motor remotely and to activate on of both speed selector switches. SC2A1 and SC2A4 series control single-phase or three-phase 400 Volt motors respectively. They restart automatically after a power failure and they feature an alarm output and motor overheating detection (TK motor contacts).
- The RTR-1 series offers five dry contact inputs for activating one of the five available speed levels. This transformer fan speed controller can therefore be fully controlled remotely. Not only the starting signal, but also the desired fan speed can be set remotely. The RTR-1 series control single-phase motors.
Transformer fan speed controllers with analogue 0-10 Volt input
A 0-10 Volt control signal is connected to the transformer fan speed controller. This control signal determines which speed level is activated (at what speed the motor will run). A 0-10 Volt control signal can be generated manually via a potentiometer. Or it can be generated automatically by a sensor. E.g. the sensor transmits the measured CO2 level as a 0-10 Volt signal.
- STVS1 and STVS4 series are transformer fan speed controllers with an analogue input. The 5 speed steps are selected via the analogue control signal (0-10 Volt). For example: when the analogue signal has a value of 3 Volt, speed 1 will be activated. when the analogue signal has a value of 5 Volt, speed 2 will be activated, etc. For demand-controlled ventilation, these speed controllers can be combined with one of the Sentera sensors with 0-10 Volt output signal. STVS1 and STVS4 series control single-phase or three-phase 400 Volt motors respectively. They restart automatically after a power failure and they feature motor overheating detection (TK motor contacts).
Transformer fan speed controllers with Modbus RTU communication
Modbus RTU (Remote Terminal Unit) is one of the most commonly used communication protocols in building and industrial automation. It is a serial communication method that allows multiple devices to be connected on a single communication line, facilitating efficient data exchange between controllers, sensors, fan speed regulators, actuators and other devices. Modbus RTU communication is many times more stable and reliable than classic 0-10 Volt signals.
- RTVS8 and RTVS1 series of transformer fan speed controllers are controlled via Modbus RTU communication. The Modbus master of the network sends the requested speed level (1 - 5) to the corresponding Modbus holding register of the RTVS8 or RTVS1 slave device. Sentera sensors and potentiometers with Modbus communication can be combined with these speed controllers. They are also compatible with SenteraWeb cloud. This offers remote access, the possibility of receiving notifications, to use the day-week scheduler for different ventilation regimes, etc. RTVS1 series require a supply voltage of 230 VAC, while RTVS8 series can operate with a supply voltage in the range of 115 – 230 VAC. This makes them more universally applicable. Both series control single-phase motors. They restart automatically after a power failure and they feature an alarm output and motor overheating detection (TK motor contacts).
Transformer fan speed controllers with temperature sensor
Controlling the fan speed based on ambient temperature is widely used in the agricultural and horticultural sectors. The product ranges below are sold in large numbers in these industries. They have proven their quality and reliability for agricultural and horticultural applications.
- GTH series of transformer fan speed controllers operate depending on the ambient temperature. In heating mode, the fan is activated when the measured temperature drops below the set temperature. When the measured temperature is higher than the selected temperature, the fan is deactivated. The unregulated output can control a water valve to regulate the flow of hot water or a relay to activate an electric heater. The unregulated output is activated simultaneously with the fan. When the fan runs, the heater is activated. In cooling mode, the functionality is inversed. Via a jumper, heating mode or cooling mode can be selected. An optional PT500 temperature probe is required to measure the ambient temperature. GTH series can be used to control single-phase motors.
- The plug & play GTTE1 series are fully pre-wired. A supply and extraction fan can be plugged in via the Schuko sockets. When the ambient temperature becomes higher then the set temperature, fan speed will increase and the heater is deactivated. When the ambient temperature drops below the set temperature, the fans stop and the heater is activated. GTTE1 series control single-phase motors.
What is an air curtain?
An air curtain is a large fan mounted above an entrance that blows a stream of air downward to separate two environmental spaces while still allowing passage and visibility through the opening. If you have ever walked through an automatic sliding door and felt a rush of air as you crossed the threshold, you have experienced an air curtain! Air curtains are commonly used in commercial or industrial settings and their main purpose is to help contain conditioned air by providing an invisible protection over commercial or industrial building doorways without limiting the access of people or vehicles.
An air curtain is a large fan mounted above an entrance that blows a stream of air downward to separate two environmental spaces while still allowing passage and visibility through the opening. If you have ever walked through an automatic sliding door and felt a rush of air as you crossed the threshold, you have experienced an air curtain! Air curtains are commonly used in commercial or industrial settings and their main purpose is to help contain conditioned air by providing an invisible protection over commercial or industrial building doorways without limiting the access of people or vehicles.
Not only does an air curtain provide significant energy savings and enhance personal comfort, but it also helps to stop the infiltration of pollutants and flying insects when applied in both industrial or commercial settings.
What does an air curtain do?
It separates different interior spaces requiring specific conditions and shields a building interior from unwanted outside conditions such as:
- Unconditioned air (not heated or cooled)
- Flying pests and the pathogens they bear
- Dirt and debris, often driven by wind
- Unpleasant odours
- Air causing discomfort for occupants
- Air that alters interior temperatures, increasing HVAC workload and operating costs, and shortening equipment lifespan.
It separates different interior spaces requiring specific conditions and shields a building interior from unwanted outside conditions such as:
- Unconditioned air (not heated or cooled)
- Flying pests and the pathogens they bear
- Dirt and debris, often driven by wind
- Unpleasant odours
- Air causing discomfort for occupants
- Air that alters interior temperatures, increasing HVAC workload and operating costs, and shortening equipment lifespan.
How does and air curtain work?
Generally, air enters the unit through the inlet grille, which may have filter functions. This air is compressed by internal fans and forced through an air outlet directed at the open doorway.
The filter protects internal components (heat exchanger, fans, electronics, etc.) from dust and particles.
The fans in an air curtain can be direct or belt-driven. The most commonly used types are centrifugal, axial, and cross-flow fans.
Some air outlets and/or lamellae are adjustable to enhance the performance of the air curtain based on specific conditions.
For heated air curtains, a coil (electric, hot/chilled water, steam, indirect or direct gas, direct expansion, etc.) is used to heat or cool the jet. Heating prevents people from feeling a cold blast of air when crossing the doorway and helps warm the incoming air.
What are the advantages an air curtain has?
Hygienic and Healthy Atmosphere: Acts as a barrier against pests and insects and airborne dust, pollution, fumes and odours thus helping for maintaining a healthy environment.
Energy Savings: Reduces energy losses from conditioned spaces and lowers the required capacity for heating and cooling systems, it also decreases building running costs and CO2 emissions.
Increased Safety: Enhances visibility and prevents collisions by eliminating physical obstructions, it facilitates evacuation through exit doorways during fires or emergencies, but also acts as a barrier against fire smoke in special applications.
Added Value: Easy access to public buildings, control of uncomfortable sensations and increased comfort.
Hygienic and Healthy Atmosphere: Acts as a barrier against pests and insects and airborne dust, pollution, fumes and odours thus helping for maintaining a healthy environment.
Energy Savings: Reduces energy losses from conditioned spaces and lowers the required capacity for heating and cooling systems, it also decreases building running costs and CO2 emissions.
Increased Safety: Enhances visibility and prevents collisions by eliminating physical obstructions, it facilitates evacuation through exit doorways during fires or emergencies, but also acts as a barrier against fire smoke in special applications.
Added Value: Easy access to public buildings, control of uncomfortable sensations and increased comfort.
Why an air curtain needs to be controlled?
Effective air curtain control is crucial for minimising energy consumption by adjusting the air curtain performance to suit real-time conditions.
Using appropriate controls alongside auxiliary devices enables users to optimise airflow, enhancing the barrier effect and preventing air infiltration through doorways.
Basic air curtain control
Basic controllers allow manual adjustment of ventilation speed and heating stages.
These can be transformer-based controllers or variable fan speed controllers. The choice depends on your needs and air curtain specifications.
Control can be realised locally or remotely, depending on your choice of controller.
Basic controllers allow manual adjustment of ventilation speed and heating stages.
These can be transformer-based controllers or variable fan speed controllers. The choice depends on your needs and air curtain specifications.
Control can be realised locally or remotely, depending on your choice of controller.
Demand-based air curtain control
Here, the technology used can be both transformer-based or TRIAC (i.e. variable fan speed controllers), but better! Advanced controllers offer automatic functioning - adjusting ventilation and/or heating based on current conditions, however, besides a controller you need other devices such as sensors, which can measure various air parameters – temperature, humidity, TVOC, CO2 or even toxic gases.
Such solutions can offer compatibility with BMS systems, external ON/OFF switches, thermostatic control, etc. Also, a variety of safety and efficiency features can be achieved for clever control!
Why air curtain clever control?
External sensors and devices enhance the air curtain performance, ensuring protection and efficiency in various scenarios.
Here, the technology used can be both transformer-based or TRIAC (i.e. variable fan speed controllers), but better! Advanced controllers offer automatic functioning - adjusting ventilation and/or heating based on current conditions, however, besides a controller you need other devices such as sensors, which can measure various air parameters – temperature, humidity, TVOC, CO2 or even toxic gases.
Such solutions can offer compatibility with BMS systems, external ON/OFF switches, thermostatic control, etc. Also, a variety of safety and efficiency features can be achieved for clever control!
Why air curtain clever control?
External sensors and devices enhance the air curtain performance, ensuring protection and efficiency in various scenarios.
For example, installing a door contact linked to the air curtain will result in the air curtain turning off or operating at a low speed and heating stage when the door is closed, conserving energy. When the door opens, the air curtain will increase ventilation speed and heating to safeguard the doorway.
Another example is connecting the air curtain to a room thermostat, which adjusts or halts heating once the desired temperature is reached.
Why are Sentera’s controllers the ideal choice for your air curtain?
Effortless installation: Our devices feature a simplified installation and wiring process, making setup quick and hassle-free.
Intuitive, user-friendly interface: Sentera provides a straightforward interface designed to facilitate ease of use for all users.
High-quality design and manufacturing: Our products are manufactured in the European Union using premium quality components. Sentera’s R&D team develops electronics with the latest trends in the field, and to ensure superior quality, we produce our enclosures in-house. This means they are specifically designed to fit the electronics perfectly.
Durability and longevity: With over 25 years in the business, our products are built to last, ensuring reliable performance for an extended period.
Resistant to moisture: Sentera’s R&D team employs the latest trends in the field to develop moisture-resistant electronics. Our in-house produced enclosures are designed specifically to protect the electronics from moisture.
Various control options available: Choose between TRIAC and transformer-based options, with manual (both local and remote control) or on-demand control available.
Modbus communication compatibility: Modbus is our company standard, ensuring robust and reliable communication.
Seamless integration with your existing Building Management System (BMS): Our controllers are designed to integrate effortlessly with your existing BMS, providing a cohesive and efficient solution.
Intuitive, user-friendly interface: Sentera provides a straightforward interface designed to facilitate ease of use for all users.
High-quality design and manufacturing: Our products are manufactured in the European Union using premium quality components. Sentera’s R&D team develops electronics with the latest trends in the field, and to ensure superior quality, we produce our enclosures in-house. This means they are specifically designed to fit the electronics perfectly.
Durability and longevity: With over 25 years in the business, our products are built to last, ensuring reliable performance for an extended period.
Resistant to moisture: Sentera’s R&D team employs the latest trends in the field to develop moisture-resistant electronics. Our in-house produced enclosures are designed specifically to protect the electronics from moisture.
Various control options available: Choose between TRIAC and transformer-based options, with manual (both local and remote control) or on-demand control available.
Modbus communication compatibility: Modbus is our company standard, ensuring robust and reliable communication.
Seamless integration with your existing Building Management System (BMS): Our controllers are designed to integrate effortlessly with your existing BMS, providing a cohesive and efficient solution.
Sentera can provide a broad range of controllers, from standard manual models to advanced systems with automatic functions and BMS connectivity. Just tell us what you need!
TRIAC speed controllers
Electronic speed controllers are also referred to as variable speed controllers or TRIAC speed controllers. They regulate the speed of AC motors continuously variable by reducing the motor voltage without steps. Electronic speed controllers operate completely silently and require no configuration before use. They are typically used to regulate fan speed. Most customers are willing to accept the disadvantage of a slightly lower energy efficiency (compared to frequency inverters) because the advantage of user-friendliness and easy commissioning is more important to them.
Completely silent fan speed controller
Electronic fan speed controllers use electronic components to reduce the motor voltage and to regulate motor speed. For this reason, they operate completely silently unlike transformer fan speed controllers. The electronic components do not generate any sounds unlike an electrical transformer (which generates a soft humming sound, caused by the electrical transformer). Electronic speed controllers can therefore be used in applications where the noise of a transformer speed controller would be perceived as disturbing.
Motor noises at low speed
The motor speed is regulated by reducing the motor voltage. This is realised by blocking parts of the supplied voltage. In technical terms this technique is called ‘Phase Angle Control’. Phase angle control technology causes that the motor voltage no longer has a perfectly sinusoidal shape, since there are pieces missing. Certainly at low speed the motor voltage will therefore be less sinusoidal. This non-sinusoidal motor voltage makes the motor noisier. Depending on the motor brand, these motor noises can be more pronounced. In most cases, it will be more noticeable at low speed.
With a transformer speed controller, the controller itself will produce a humming sound, but the motor will operate quietly. With an electronic speed controller, it is the other way around. Here, the motor makes more noise, while the controller is quiet.
Continuously variable speed control
Electronic speed controllers regulate fan speed by reducing the motor voltage continuously variable (without steps). Transformer fan speed controllers also regulate the motor speed by reducing the motor voltage. The difference is that transformer fan speed controllers do this in steps, while electronic fan speed controllers do this continuously. Both types of speed controllers are suitable for voltage-controllable motors. These are electric motors where the speed can be controlled by lowering the motor voltage while the frequency remains constant. Most fans with an AC motor can be controlled in this way. Both TRIAC and transformer fan speed controllers can be used in applications where the torque decreases with speed, such as fan speed control.
Phase Angle Control regulates motor speed
Electronic fan speed controllers use electronic components to control motor speed. The most important one is the TRIAC or TRiode for Alternating Current. A TRIAC is visualised in the image at the right side. It is the black electronic component with the three pins. Electronic fan speed controllers are also referred to as TRIAC controllers. A TRIAC is a three-electrode semiconductor that can be seen as a switch. Either it allows the electric current to pass or either it blocks the flow of electric current.
The more precisely the TRIACs are controlled, the less noticeable the additional motor noise will be. For this reason, the latest Sentera electronic fan speed controllers are all equipped with advanced microprocessors. This makes it possible to reduce additional motor noise to an absolute minimum. Cheaper variants of electronic fan speed controllers usually control the TRIACs with much lower accuracy. This results in additional motor noises and faster wear of the electric motor.
Typically, TRIACs can switch electric currents with a maximum current of up to 10 A. For this reason, this type of controller is usually only available for single-phase motors.
TRIAC controllers require a minimum load
A TRIAC has the special property that it needs a minimum load before it can function. If no load (a motor, a light bulb, …) is connected to the speed controller, it will not function. Only when a minimum electrical current can flow (typically 10% of the maximum current), the electronic speed controller will function normally. So if you want to verify whether the speed controller is functioning correctly, a load must be connected! Without this load, it appears as if the speed controller is defective because the TRIACs cannot conduct. This is not the case with a transformer speed controller. Transformer speed controllers do work without a load.
User-friendly and easy commissioning
The electronic circuit that controls the TRIACs, makes it possible to offer additional setting options. These additional setting options are usually not available on less advanced transformer speed controllers. For example, most TRIAC controllers allow the minimum or maximum speed to be changed according to the needs of the application. Since fans are usually oversized, it is important in many applications to adjust the maximum speed. Thanks to these additional setting possibilities, this type of controller can be better optimized for the application than transformer fan speed controllers. Some TRIAC speed controllers are deliberately kept simple to keep the price down, other series offer more setting options. There are two ways to adjust settings on Sentera electronic speed controllers: via Modbus RTU communication (software) or via a trimmer (small potentiometer, mounted on the printed circuit board).
In most Sentera products, settings can be changed via software, by adjusting a value in a Modbus holding register. A Modbus network consists of a master device and at least one slave device. The master device can be a PC with configuration software, the slave device can be the speed controller. The Modbus master device can change certain values in the slave device and read out other values. This makes it possible, for example, to change the minimum speed by adjusting the value of the corresponding Modbus Holding register.
Another example: in some electronic fan speed controllers the operation method is adjustable. This makes it possible to change the behaviour of the fan speed controller by writing a different value in the corresponding Modbus Holding register. By default, the operation mode is ‘from low to high (value 1)’, but it can be changed into ‘from high to low' by adjusting the value of the Holding register towards 2. If the fan speed controller is connected to the SenteraWeb cloud, it is even possible to read out or to adjust the values of the Modbus Holding registers remotely. This can only be done by the configurator of the installation.
Some basic Sentera TRIAC speed controllers do not feature Modbus communication to keep the price down. In these devices it is usually possible to adjust the minimum or maximum speed via a trimmer, mounted on the printed circuit board.
Frequency inverter versus electronic fan speed controller
What is the difference between a frequency inverter and an electronic speed controller? In short, a TRIAC controller is cheaper and easier to use, while a frequency inverter will control the electric motor in a more energy-efficient way, especially at low speed.
But what are the real differences? This is not so easy to explain in a non-technical way. Here is an attempt: A TRIAC speed controller regulates the motor speed by reducing the amount of incoming power before sending it to the motor (reducing the motor voltage). On the other hand, a frequency inverter not only reduces the power but also changes how fast the power cycles (it also changes the frequency of the motor voltage). By adjusting both the frequency and the voltage, the motor torque can be controlled in addition to the motor speed. Motor torque means the force of the electric motor. So the frequency inverter can control both how fast the motor rotates and how strong it is. By optimizing motor speed and torque, energy can be saved at lower speeds.
Explaining the difference between a Frequency inverter and TRIAC speed controller in a more technical way would sound like this: A frequency inverter does not only reduce the motor voltage, but it also changes the frequency of the motor voltage. This makes it possible to keep the ratio between motor voltage (V) and frequency (f) constant. This control algorithm is also referred to as constant V/f control.
If the motor voltage is reduced without adjusting the frequency - this is what a TRIAC speed controller does - the magnetic flux decreases. Since motor torque is directly related to the magnetic flux in the motor, this leads to a reduction in motor torque at lower speed. The motor may struggle to drive the load, especially at lower speeds, and could even stall under heavy load conditions. This problem will not occur in applications requiring low starting torque. Since a fan usually requires a relatively low starting torque, this type of applications can usually be controlled by a TRIAC speed controller.
There are also applications that require a high starting torque. For example, hoisting applications require maximum motor torque from minimum speeds. As soon as the mechanical brake is released, the electric motor must immediately deliver full torque to keep the load under control. For such applications, a frequency controller is required. A TRIAC speed controller is not sufficient here.
With the TRIAC speed controllers we aim at applications in the HVAC industry, such as controlling fans or centrifugal pumps. Most fans follow a quadratic torque curve. This means that the required motor torque increases quadratically as the speed increases. At low speeds it is easy to get the fan running. As fan speed increases, more motor torque is needed to further accelerate the fan. This increase in required motor torque is not linear but quadratic. For this reason, a lot of energy can be saved by reducing fan speed if possible.
Optimizing the magnetic flux is the reason why a frequency inverter can control the motor in a more energy-efficient way. Reducing the motor voltage while keeping the frequency constant causes the motor to draw more electrical current at low speed to compensate for the reduced magnetic flux. This increased current leads to higher losses in the motor windings, resulting in excessive heat. Keeping the V/f ratio constant ensures that the motor operates more energy efficiently, with optimal current levels. The motor produces sufficient torque without drawing excessive current, which minimizes heat generation and avoids overheating.
Why TRIAC speed controllers remain interesting
Sentera TRIAC speed controllers are still widely used to regulate fan speed. Their ease of use, simple construction and attractive price are the main advantages. The fan speed can be adjusted continuously variable (without steps). The fan speed controller operates completely silently. Disadvantages of this technology are the lower energy efficiency compared to frequency inverters and the possibility of motor noises at low speed. Sentera TRIAC speed controllers are designed to minimise these disadvantages as much as possible. Due to the very accurate control of the TRIACs using microcontrollers, the motor noises are in most cases hardly noticeable.
Product range of Sentera TRIAC fan speed controllers
Sentera is one of the leading manufacturers of fan speed controllers. For two decades, our electronic fan speed controllers have been the standard in the HVAC world. Quality and user-friendliness has always been our top priority. Due to the great success, many variants were created. As a result, it is not always easy to get an overview of this product range. The most important properties of the different series are briefly summarized below.
Sentera electronic fan speed controllers are available with a maximum current rating of 10 A. They feature a high-quality plastic enclosure. The versions with higher current ratings are equipped with a metal cooling fin for heat dissipation. The enclosure is manufactured in our own Sentera plastics factory from flame-retardant ABS plastic. The cooling fin guarantees sufficient heat dissipation and is calculated for the maximum power of the controller.
Electronic fan speed controllers with built-in potentiometer
For manual motor control, we offer the electronic fan speed controllers with built-in control switch on the front panel. They control single-phase voltage controllable motors with a maximum current of 10 A. These speed controllers in particular are easy to install and operate. Motor speed can be adjusted via the controls on the front panel.
- Residential applications - for residential applications, we recommend the SDX and SDY series. They control single phase motors with a maximum current of 3 A. Both versions are easy to install on a wall or flat surface or in a standard European wall-socket. The minimum speed can be adjusted via an internal trimmer.
SDX-1-x5-DM series offer more flexibility thanks to the Modbus RTU communication. Via the Modbus holding registers, additional settings can be made. This makes it possible for example to inverse the operation from 'high to low' speed into 'low to high' speed. - Warehouses and industrial environments - for logistics or industrial applications we recommend the ITR-9 series. They control single phase motors with a maximum current of 10 A. The minimum motor speed can be adjusted via an internal trimmer on the PCB. The integrated ON-OFF switch is placed at the side of the enclosure. If necessary, this ON-OFF switch can be disabled. The enclosure is designed for surface mounting and offers an IP54 protection degree against ingress of dust and humidity.
The similar ITRS9 series look almost identical, but they feature two extra inputs for remote start-stop commands, one extra output for alarm notifications and the possibility to monitor the motor thermal contacts (temperature sensor integrated in the motor windings to detect motor overheating).
SLM series can be seen as ITR-9 fan speed controllers with an extra switch on the front panel to control the lighting. - DIN rail mounting in an electrical cabinet - Following fan speed controllers are designed for installation in an electric cabinet. DRX and DRY series feature a rotary knob on the front panel to set the desired fan speed. They control single phase motors with a maximum current of 2,5 A.
DRE series features Modbus RTU communication and a 3-button keyboard interface.
Electronic fan speed controllers with analogue input
For remote control, we offer electronic fan speed controllers with analogue 0-10 Volt input. These versions do not have built-in control switches. They require an analogue 0-10 Volt control signal to set the desired fan speed. An analogue signal is typically generated by an external potentiometer or HVAC sensor. At 0 Volts the motor will operate at minimum speed. As the analogue signal increases towards 10 Volts the motor will accelerate to maximum speed (at 10 Volts).
Controllers for single-phase 230 Volt voltage controllable motors:
- Surface mounting - A first group of electronic speed controllers with analogue input has a housing suitable for wall mounting. The housing offers IP54 protection against moisture and dirt ingress. The EVS series are the basic version within this group. The EVSS series offer an additional input for remote ON-OFF commands as well as an input for monitoring the thermal motor contacts (if the motor is equipped with them). If motor overheating is detected, the controller goes into safety mode, activates the alarm output and stops the motor.
- DIN rail mounting in an electrical cabinet - This group of electronic speed controllers with analogue input has a housing suitable for DIN rail mounting. Given the IP20 degree of protection against moisture and dirt, mounting in an electrical cabinet is necessary. The MVS series are the basic version within this group. The MVSS series offer an additional input for remote ON-OFF commands as well as an input for monitoring the thermal motor contacts (if the motor is equipped with them). If motor overheating is detected, the controller goes into safety mode, activates the alarm output and stops the motor.
Controllers for three-phase 400 Volt voltage controllable motors:
- TVSS5 series are electronic fan speed controllers with analogue input. The TK monitoring function protects motors against overheating. Their enclosure allows DIN rail mounting. They control three-phase voltage controllable motors with a maximum current of 6 A.
Greenhouse and climate controllers
Sentera also offers electronic fan speed controllers with (built-in) temperature sensor. They regulate single-phase motor speed based on the ambient temperature. Typically, they are used to cool greenhouses or regulate the climate in grow rooms. As the temperature increases, the motor speed increases. Below the temperature setpoint the motor speed is either minimum speed or either the motor stops.
- Grow room climate controller - GTEE1 series are delivered fully pre-wired and are therefore immediately ready for use. The regulated output can be used to control fan speed. As the ambient temperature exceeds the set temperature, the fan speed will increase to provide more cooling. The unregulated output can be used to activate a heating element if the ambient temperature drops below the set temperature.
- Greenhouse climate controller - GTE series regulate fan speed for cooling purposes. As the ambient temperature exceeds the set temperature, the fan speed will increase to provide more cooling. GTE series are available in -DT version and in -DM version. The GTE -DT version is delivered fully pre-wired and is immediately ready for use. the GTE -DM version is not pre-wired (an optional PT500 temperature sensor is required) but offers Modbus RTU communication to simplify adjustment of settings. Remote control via Modbus RTU communication is possible here. The GTE-1 series allow the temperature setpoint to be set in the range of 15-35 °C. The GTE21 series have a temperature setpoint that can be set in the range of 5-35 °C.
The printed circuit boards of electronic devices are exposed to increasingly demanding ambient conditions. The enclosures protecting the sensitive electronic components are subject to various requirements – ingress protection degrees, temperature, humidity, etc. In line with industry trends, Sentera never fails to meet all the requirements – from various mounting options to protection classes. And since we develop our enclosures in-house, besides offering surface and flush mounting options, we develop enclosures for DIN rail mounting for control cabinet applications.
DIN rails are metal rails that conform to industry standards and are used to mount industrial processing equipment. Installation is very simple – just mount your Sentera device onto a standard 3,5 mm DIN rail and lock it using the pin at the bottom of the device.
Why DIN rail enclosures?
DIN rail electronics have been around for a long time and are becoming increasingly popular in industrial applications across a wide range of industries. They make the perfect packaging for electronics. Not only do they protect the electronics, but they can also be easily mounted onto standard DIN rails and integrated into the control cabinet.
DIN rail electronics have been around for a long time and are becoming increasingly popular in industrial applications across a wide range of industries. They make the perfect packaging for electronics. Not only do they protect the electronics, but they can also be easily mounted onto standard DIN rails and integrated into the control cabinet.
When it comes to HVAC systems, DIN rail enclosures offer specific advantages that align well with the needs of these systems:
Compact and organized installation: HVAC systems often require the integration of various control components, such as thermostats, sensors, relays, and controllers. DIN rail enclosures provide a compact and organized way to house these components within control panels, ensuring that space is efficiently used and the layout remains clean and manageable.
Ease of maintenance and troubleshooting: access to individual components is simplified for regular maintenance and troubleshooting, allowing for quick diagnostics and replacement of faulty parts without disturbing other components.
Modularity and expandability: As HVAC systems are upgraded or expanded to meet changing building requirements, the modular nature of DIN rail enclosures allows for easy addition or replacement of components. This flexibility is crucial for adapting to new technologies or changes in building use.
Improved wiring and connectivity: The organized layout provided by DIN rail enclosures simplifies wiring for HVAC control systems.
Enhanced safety: Properly housed components in DIN rail enclosures reduce the risk of electrical faults, such as short circuits, which is vital for the safe operation of HVAC systems. This is especially important in systems that are critical to maintaining air quality and temperature control in buildings.
Compact and organized installation: HVAC systems often require the integration of various control components, such as thermostats, sensors, relays, and controllers. DIN rail enclosures provide a compact and organized way to house these components within control panels, ensuring that space is efficiently used and the layout remains clean and manageable.
Ease of maintenance and troubleshooting: access to individual components is simplified for regular maintenance and troubleshooting, allowing for quick diagnostics and replacement of faulty parts without disturbing other components.
Modularity and expandability: As HVAC systems are upgraded or expanded to meet changing building requirements, the modular nature of DIN rail enclosures allows for easy addition or replacement of components. This flexibility is crucial for adapting to new technologies or changes in building use.
Improved wiring and connectivity: The organized layout provided by DIN rail enclosures simplifies wiring for HVAC control systems.
Enhanced safety: Properly housed components in DIN rail enclosures reduce the risk of electrical faults, such as short circuits, which is vital for the safe operation of HVAC systems. This is especially important in systems that are critical to maintaining air quality and temperature control in buildings.
The ease of installing and organizing components on a DIN rail reduces labour costs and the complexity of setting up HVAC control panels. This can be particularly beneficial in large-scale HVAC installations where time and efficiency are key factors.
Sentera offers a wide selection of DIN rail mounted products, starting from the simplest to the most complex:
HVAC controllers
The DRPUM universal HVAC controller is a versatile programmable controller designed for specific applications, requiring dedicated firmware.
Variable fan speed controllers
Manual control
The DRE controller is intended for single-phase voltage controllable motors with a maximum current of 2,5 A. It regulates fan speed by varying the motor voltage via phase angle control - Triac technology. The power supply is 230 VAC. The minimum and maximum speed can be adjusted via Modbus RTU. The motor voltage is regulated via the 3-button keyboard in the range between the selected minimum and maximum speed. Kick start or soft start acceleration can be selected via Modbus RTU.
Manual control
The DRE controller is intended for single-phase voltage controllable motors with a maximum current of 2,5 A. It regulates fan speed by varying the motor voltage via phase angle control - Triac technology. The power supply is 230 VAC. The minimum and maximum speed can be adjusted via Modbus RTU. The motor voltage is regulated via the 3-button keyboard in the range between the selected minimum and maximum speed. Kick start or soft start acceleration can be selected via Modbus RTU. The DRX series are electronic fan speed controllers. They control single-phase voltage controllable motors with a maximum current of 2,5 A. The fan speed is regulated by varying the motor voltage via phase angle control - Triac technology. The motor voltage can be manually regulated via the rotary knob from maximum to minimum.
The DRY series are electronic fan speed controllers. They control single-phase voltage controllable motors with a maximum current of 2,5 A. The fan speed is regulated by varying the motor voltage via phase angle control - Triac technology. The motor voltage can be manually regulated via the rotary knob from minimum to maximum.
Analogue input motor control
The MVS-1 series are electronic fan speed controllers with analogue input. They regulate the speed of single-phase voltage controllable motors with a maximum current of 10 A. The AC fan speed is controlled by varying the motor voltage via phase angle control - Triac technology. The minimum and maximum speed is adjustable via trimmers. The motor voltage can be regulated via the analogue input or via Modbus RTU. Kick start or soft start acceleration and the operating mode is selectable via Modbus RTU.
The MVSS1 series are electronic fan speed controllers with analogue input. Their TK monitoring function deactivates the motor in case of overheating. They regulate the speed of single-phase voltage controllable motors with a maximum current of 10 A. The AC fan speed is controlled by varying the motor voltage via phase angle control - Triac technology. The minimum and maximum speed is adjustable via trimmers. The motor voltage can be regulated via the analogue input or via Modbus RTU. Kick start or soft start acceleration and the operating mode is selectable via Modbus RTU. A remote start/stop command can be generated via the digital input.
The TVSS5 series are electronic fan speed controllers with analogue input. The TK monitoring function protects motors against overheating. They control three-phase voltage controllable motors with a maximum current of 6 A. The fan speed is regulated by varying the motor voltage via phase angle control - Triac technology. The minimum and maximum speed is adjustable via trimmers. The motor voltage can be regulated via the analogue input or via Modbus RTU. Kick start or soft start acceleration and the operating mode is selectable via Modbus RTU. A remote start/stop command can be generated via the digital input.
The TVSS5 series are electronic fan speed controllers with analogue input. The TK monitoring function protects motors against overheating. They control three-phase voltage controllable motors with a maximum current of 6 A. The fan speed is regulated by varying the motor voltage via phase angle control - Triac technology. The minimum and maximum speed is adjustable via trimmers. The motor voltage can be regulated via the analogue input or via Modbus RTU. Kick start or soft start acceleration and the operating mode is selectable via Modbus RTU. A remote start/stop command can be generated via the digital input.
Frequency inverters
The FI series of frequency drives are designed to work with a wide range of motor types, making them highly versatile for various HVAC applications. They are compatible with both induction motors (AC motors) and permanent magnet motors, providing precise speed control and energy efficiency across different motor technologies. Our range covers single ad three-phase motors control and 230 VAC and 400 VAC supply. They feature both DIN rail and keyhole mounting options.
The FI series of frequency drives are designed to work with a wide range of motor types, making them highly versatile for various HVAC applications. They are compatible with both induction motors (AC motors) and permanent magnet motors, providing precise speed control and energy efficiency across different motor technologies. Our range covers single ad three-phase motors control and 230 VAC and 400 VAC supply. They feature both DIN rail and keyhole mounting options.
Power supplies
Switch mode power supplies - 24 VDC
The DRPS8-24-40 is a 24-volt switched-mode power supply (SMPS). This module accepts an input voltage of 85–264 VAC / 50–60 Hz. The maximum load on this switched mode power supply is 40 Watts. The loads can be connected via the terminal block or via the RJ45 connector.
Switch mode power supplies - 24 VDCThe DRPS8-24-40 is a 24-volt switched-mode power supply (SMPS). This module accepts an input voltage of 85–264 VAC / 50–60 Hz. The maximum load on this switched mode power supply is 40 Watts. The loads can be connected via the terminal block or via the RJ45 connector.
The DHDR8-24-36 is 24 Volt power supply module is an electrical device used to convert input voltage (typically AC mains voltage or a different DC voltage) into a stable 24 VDC (volts of direct current) output voltage. The device accepts an input voltage of 85–264 VAC / 50–60 Hz and the maximum load of 36 W can be connected to it.
Linear power supplies
The SATD1 series of safety transformers are linear power supplies, which means they can only produce a voltage lower than the supply (input) voltage. Sentera’s linear power supply modules utilize transformer technology, thanks to which they operate noiselessly. This series is comprised of compact single-phase safety isolating transformers encapsulated in a plastic modular enclosure. Safety transformers are used for electrical isolation of the input (mains supply) and output (12 or 24 VAC). They are suitable for creating SELV (safety extra-low voltage) and PELV (protective extra-low voltage) circuits by limiting the output voltage. The units are short circuit and overload protected with a built-in PTC in the primary winding which automatically restores power when the transformer is cooled down or the load is removed.
Linear power supplies
The SATD1 series of safety transformers are linear power supplies, which means they can only produce a voltage lower than the supply (input) voltage. Sentera’s linear power supply modules utilize transformer technology, thanks to which they operate noiselessly. This series is comprised of compact single-phase safety isolating transformers encapsulated in a plastic modular enclosure. Safety transformers are used for electrical isolation of the input (mains supply) and output (12 or 24 VAC). They are suitable for creating SELV (safety extra-low voltage) and PELV (protective extra-low voltage) circuits by limiting the output voltage. The units are short circuit and overload protected with a built-in PTC in the primary winding which automatically restores power when the transformer is cooled down or the load is removed.
Modbus RTU repeater and power supply
The DPOM8-24-20 is a 24 VDC switch mode power supply featuring a built-in Modbus RTU repeater. It offers protection against short circuit, overload and overvoltage. The maximum load is 900 mA or 20 W. The 24 VDC supply is only available via the output channel. The Modbus RTU communication of both channels is reinforced by the built-in half-duplex line repeater.
Modbus distribution boxes
The DMDBM22 is a distribution box for Modbus RTU communication and supply voltage. It can be used to interconnect Sentera devices. It has 10 channels for 24 VDC powered devices and 12 channels for 3,3 VDC powered devices. Modbus RTU communication and 24 VDC supply voltage are transmitted via the RJ45 sockets. Modbus RTU communication and 3,3 VDC supply voltage are transmitted via the RJ12 sockets. External power supply is required for both 24 VDC and 3,3 VDC supply.
The DLDBM22 is a distribution box for Modbus RTU communication and supply voltage used to interconnect Sentera devices. It has 10 channels for 24 VDC powered devices and 12 channels for 3,3 VDC powered devices. Modbus RTU communication and 24 VDC supply voltage is transmitted via the RJ45 sockets. Modbus RTU communication and 3,3 VDC supply voltage is transmitted via the RJ12 sockets. If an external 24 VDC power supply is connected to one of the RJ45 sockets, a supply voltage of 3,3 VDC will be available via the RJ12 sockets. The 3,3 VDC supply voltage is automatically derived from the 24 VDC supply voltage.
Converters
The DRM-M series are relay output modules for Modbus RTU networks. They feature 2 or 4 C/O relays with a normally open and normally closed contact. The status of the relays can be controlled by Modbus RTU communication.
The DIO-M series an Input-Output module for Modbus RTU networks. You can choose between 4 digital inputs and 4 digital outputs or 4 digital inputs and 2 relay outputs. The digital outputs are activated via a Modbus RTU. The status of the digital inputs is translated into Modbus RTU registers. The relay outputs can be triggered via a Modbus RTU register.
The DRM-M series are relay output modules for Modbus RTU networks. They feature 2 or 4 C/O relays with a normally open and normally closed contact. The status of the relays can be controlled by Modbus RTU communication.
The DIO-M series an Input-Output module for Modbus RTU networks. You can choose between 4 digital inputs and 4 digital outputs or 4 digital inputs and 2 relay outputs. The digital outputs are activated via a Modbus RTU. The status of the digital inputs is translated into Modbus RTU registers. The relay outputs can be triggered via a Modbus RTU register.
The DDACM series are analogue to digital (Modbus RTU) converter modules supplied via Power over Modbus. The DADCM/08 product version has four analogue / modulating and four analogue inputs while the DADCM/44 version has four analogue / modulating inputs and four temperature inputs. The type of input is selected via Modbus RTU communication. The input values are transferred to Modbus RTU.
Sentera internet gateways
The DIG-M-2 internet gateway connects a single Sentera device or a network of devices to the Internet in order to configure or monitor them via SenteraWeb. The DIG-M-2 makes wireless or wired connection with the Internet router. The unit has 2 Modbus RTU channels - a Master channel to communicate with the connected Slave devices, and a Slave channel to make the unit accessible for a Master controller or a BMS.
The DIGWM is an internet gateway to connect a stand-alone Sentera device or a network of devices to the Internet in order to configure or monitor them via SenteraWeb. The DIGWM makes wireless connection with an existing Wi-Fi network. The unit has 2 Modbus RTU channels - a Master channel to communicate with the connected Slave devices, and a Slave channel to make the unit accessible for a Master controller or a BMS.
DIN rail enclosures in HVAC systems provide an organised, reliable and efficient way to house and protect control components, making them an ideal choice for ensuring the smooth operation and longevity of HVAC systems. Whether you’re upgrading an existing system or planning a new installation, Sentera’s DIN rail enclosures provide the perfect balance of performance and practicality. Choose Sentera for your HVAC control needs, and experience the difference in quality and reliability.
HVAC products undergo a variety of tests to ensure they meet safety, efficiency and performance standards. By following these testing procedures, manufacturers can ensure that their HVAC products are safe, efficient, and effective for consumer use. Sentera is one of the leading manufacturers of control solutions for HVAC and ventilation systems. Our customers praise our control solutions because they are innovative and at the same time easy to use. We make no concessions in terms of quality. To guarantee this quality, we do all sub-assemblies as well as software development in-house. So, testing our products can never be overstated.
Our products undergo comprehensive testing to ensure their durability and reliability in various environmental conditions. You can trust that our sensors are designed to withstand the harshest environments and deliver accurate readings every time thanks to our climate testing chamber which provides reproducible and certified results under accelerated conditions, giving you peace of mind that your products will perform optimally regardless of the temperature.
What is more, our climate chamber is housed in Sentera’s cleanroom especially designed to maintain a controlled environment with minimal air contamination. It features strict regulations regarding airflow, temperature, humidity, and the concentration of airborne particles.
How we guarantee the quality of our sensors
In any season, in any climatic zone – we want to make sure our products can withstand a variety of ambient conditions during manufacturing, transport, storage and use. Our environmental simulation facilities help us test the influence of ambient conditions on product properties, function and lifespan of your products. Therefore, we undergo diligent testing before shipping our products.
The primary objective of this testing is to evaluate the performance, accuracy, and response time of our sensors. These three critical parameters can be evaluated simultaneously, ensuring that our sensors meet the highest standards of quality and reliability.
Our accuracy evaluation test enables us to assess the measurement error of the sensing elements (T, rH, CO2, TVOC, LPG and CO) embedded in our sensors as part of the complete system.
Meanwhile, our response time evaluation test allows us to assess the speed of the sensing element's reactions to changes in the environment, ensuring that our sensors provide accurate and timely data.
In addition to accuracy and response time evaluation tests, our sensors undergo a comprehensive performance evaluation test. This test enables us to assess the adequacy of the behaviour of the sensing elements (T, rH, CO2, TVOC, LPG and CO) and the entire device under different climate conditions and supply voltages.
By subjecting our sensors to these extreme conditions, we can ensure that they are designed to withstand the harshest environments and deliver accurate readings every time.
In any season, in any climatic zone – we want to make sure our products can withstand a variety of ambient conditions during manufacturing, transport, storage and use. Our environmental simulation facilities help us test the influence of ambient conditions on product properties, function and lifespan of your products. Therefore, we undergo diligent testing before shipping our products.
The primary objective of this testing is to evaluate the performance, accuracy, and response time of our sensors. These three critical parameters can be evaluated simultaneously, ensuring that our sensors meet the highest standards of quality and reliability.
Our accuracy evaluation test enables us to assess the measurement error of the sensing elements (T, rH, CO2, TVOC, LPG and CO) embedded in our sensors as part of the complete system.
Meanwhile, our response time evaluation test allows us to assess the speed of the sensing element's reactions to changes in the environment, ensuring that our sensors provide accurate and timely data.
In addition to accuracy and response time evaluation tests, our sensors undergo a comprehensive performance evaluation test. This test enables us to assess the adequacy of the behaviour of the sensing elements (T, rH, CO2, TVOC, LPG and CO) and the entire device under different climate conditions and supply voltages.
By subjecting our sensors to these extreme conditions, we can ensure that they are designed to withstand the harshest environments and deliver accurate readings every time.
Every Sentera sensor series undergoes a rigorous testing process, consisting of multiple parts and simulation different environmental conditions, depending on the sensor type (T, rH, CO2, TVOC, LPG and CO).
By performing a temperature dependence test we evaluate the accuracy and performance of our T, rH, CO2, TVOC, LPG and CO sensors within the operational temperature range of the sensors series. This test ensures that our sensors can deliver accurate readings even in extreme temperature conditions.The relative humidity dependence test assesses the accuracy and performance of our T, rH, CO2, TVOC, LPG and CO sensors within the operational relative humidity range. This test ensures that our sensors can provide accurate readings, even in environments with varying levels of humidity.
Depending on the sensor type, we use different gases (CO2, TVOC, LPG and CO) to simulate real operating conditions and thus check the accuracy of the sensing elements and guarantee precise reading and long-term reliability.
Our engineers also implement voltage stress test to evaluate the performance of our devices at the minimum and maximum supply voltages under extreme temperature conditions of -10 °C and 60 °C. This test ensures that our sensors can withstand voltage fluctuations and deliver reliable readings even in challenging conditions.
At every stage of our testing process, we strive to ensure that our sensors meet the highest standards of quality and reliability. Choose our sensors and experience the difference in performance and accuracy.
What is an electric motor?
An electric motor is a device that converts electrical energy into mechanical one. This occurs through the interaction of a magnetic field and electric current in the motor's windings (coils), which produces a force, or torque, on the motor shaft. The motor consists of two main parts: the rotor, which moves, and the stator, which remains stationary. In most traditional AC motors, the windings are located in the stator. When alternating current flows through the stator windings, it creates a rotating magnetic field. The rotor’s magnetic field follows this rotating stator field, causing the motor to spin.
Asynchronous motors typically feature a squirrel-cage rotor, where the rotating magnetic field of the stator induces currents in the rotor windings, according to Faraday’s law of induction. These currents in turn generate the rotor’s magnetic field. In contrast, synchronous motors often have rotors with permanent magnets, which directly follow the rotating stator field.
Positive and negative sides of using variable frequency drives in HVAC industry
In some applications (such as robots on production lines, medical equipment, laboratory instruments and similar) the precise speed control is crucial for both keeping the quality of the installed fans and control devices, and for delivering precisely measured ranges of temperature, relative humidity and others in order to take on-time actions to preserve the comfort of inhabitants. Frequency inverters can provide highly accurate speed control, enabling precise operations and production in these applications. The primary advantage of a frequency inverter lies in its ability to enhance energy efficiency and optimize motor performance. By dynamically adjusting the motor's speed to match the actual requirements of a task, a frequency inverter prevents unnecessary energy consumption. This is particularly beneficial in applications where the load changes dynamically or when a constant speed is not essential, such as in heating, ventilation and air conditioning systems.
Moreover, frequency inverters extend the lifespan of motors by reducing wear and tear associated with abrupt starts and stops. They also provide precise control, improving the overall accuracy and quality of processes. In industrial applications, where electric motors play a crucial role, integrating frequency inverters contributes to cost savings, environmental sustainability, and more reliable operation of machinery. In essence, a frequency inverter is like a smart accelerator for electric motors, offering flexibility, efficiency, and longevity.
The major difference between a frequency converter and a fan speed controller is not easy to explain in non-technical terminology. Here's an attempt anyway. A frequency converter offers optimal motor control because it can regulate not only the voltage, but also the frequency. This has the advantage that the motor can be controlled much more efficiently and accurately. Disadvantages of this technology are its complexity and price. A fan speed controller can only regulate the motor voltage. This is done simply by cutting away parts of the supplied voltage with TRIAC technology (phase angle control). The advantage of this is that fewer expensive electronic components are required and that the device can be put into use immediately. A frequency controller must first be configured before it can be put into use.
Negative sides - Electromagnetic pollution
Electromagnetic pollution caused by frequency inverters refers to the unintended electromagnetic interference they may generate, potentially affecting nearby electronic devices and communication systems. This interference can manifest as disruptions, glitches, or malfunctions in radios, TVs, and other sensitive equipment. The risks associated with electromagnetic pollution include compromised performance and reliability of nearby electronic devices, which may be critical in residential or industrial settings.
To avoid these issues, it is crucial to implement mitigation measures. The electromagnetic compatibility (EMC) filters that are standard integrated in our frequency inverters, help to suppress electromagnetic interference, preventing it from radiating into the surrounding environment. Proper grounding and shielding of cables also play a role in minimizing electromagnetic pollution. Installation practices, such as maintaining appropriate distances between sensitive equipment (e.g. data cables, analogue signals, communication cables, etc.) and potential sources of electromagnetic pollution (e.g. power cables, electric motors, frequency inverters, etc.) can further reduce the risk of interference.
Pulse Width Modulation for optimal motor control
Frequency inverters, also known as Variable Speed Drives, provide precise speed control for AC fans through infinitely variable adjustments. Similarly, as described earlier, electronic fan speed controllers offer this capability too. What divides them apart? A frequency inverter employs Pulse Width Modulation (PWM) with IGBT technology to regulate both motor voltage and frequency. This method ensures exceptionally quiet motor operation and nearly perfect sinusoidal motor voltage under all conditions. Depending on its settings, a frequency inverter can operate silently itself.
However, because a frequency inverter switches between direct current and alternating current frequently, it can introduce electromagnetic interference (EMC) to other devices on the same power grid. Expensive specialized filters have been developed to mitigate this EMC pollution. Moreover, frequency inverters generally involve higher initial configuration costs due to their inherent complexity compared to other fan speed controllers. In summary, while frequency inverters are more costly and complex to set up, potentially requiring additional tools, they offer extremely precise motor control. These controllers are highly energy-efficient and capable of handling substantial motor currents.
The requested motor speed can be adjusted via the controls that are integrated onto the device itself (potentiometer or push buttons). It is also possible to adjust the motor speed remotely via Modbus RTU or an analogue control signal (e.g. 0-10 Volt signal).
Thermal protection for AC motors
An AC motor is a robust device with a long service life. However, operating an AC motor at low speed for a longer period of time is not without risks. At low speed, the motor cools itself less. This can cause overheating of the motor windings, which can cause degradation of its insulation. This can cause electric leakages, short circuits, and eventually, motor failure. To prevent motor failure, it is important to prevent the motor from being overheated. For this purpose, many AC motors are equipped with thermal contacts, also called TK. These thermal contacts measure the temperature in the motor windings. In case of the motor overheating, the TK contacts open. Some fan speed controllers provide extra protection against overheating via their TK monitoring function, which deactivates the motor in case of overheating to prevent motor damage. At the same time, the alarm output will be enabled to indicate a motor problem.
Positive sides from regulating the fan speed
A motor at full speed is noisy, consumes much energy, costs money, and exacerbates heat losses. If we decrease fan speed, the motor will make less noise, will consume less energy, and this will, in turn, reduce the operational costs of the ventilation system. All this serves to increase the comfort of residents. Why would we not simply buy a smaller motor if that were the case? A motor needs to be at full capacity, like when there is a large crowd of people in a single room. A motor will also need to run faster when the temperature or relative humidity differs too greatly from the outdoors. In other words, to regulate the Indoor Air Quality, the motor and fan speeds need to be adjusted.
Energy savings – The fan speed must be constantly monitored and controlled in order to have sufficient fresh air supply! But even a slight reduction in fan speed might cause a major problem - the electrical energy consumption of the fan grows bigger. A typical HVAC fan follows a quadratic torque curve. Depending on the motor type, a reduction of 25 % air volume flow corresponds with 50 % less energy consumption. In addition, a lower air volume flow rate also results in a quieter operation.
Extended service life - The more air that passes through the filters, the higher the risk of contamination of the filters. A reduced air volume flow rate also has a positive effect on the service life of the mechanical parts of the fan.
Reducing heat losses - In colder climates, extracted warm indoor air is replaced by fresh air that can be much colder. That means that if we ventilate, we would need to spend more energy on heating. Modern ventilation systems are equipped with a heat exchanger to minimize such heat losses. Nevertheless, additional energy can be saved by reducing the fan speed when possible.
How to connect to SenteraWeb?
In order to connect your frequency drive to the SenterWeb HVAC cloud platform to configure, add new information or just to monitor the measured values and to receive on-time notifications in case of trouble, you’ll need the ADPT-3SM-FI adapter. This adapter is used to facilitate the connection between the frequency inverter and your computer. Just install the drive, add your basic information in your profile in the SenteraWeb platform and start monitoring your installation.
For further information over the different types of frequency inverter, go to the product category on the website. To see different examples of combining and installing frequency inverters, check the solutions category on www.sentera.eu/solutions.
Sentera offers wide range of solutions, suitable for temperature, humidity and air control. In this article, we will show an example of air control in wide-space, specialised storages for vegetables. How can a single solution be suitable for climate control in both potato and onion storage areas? The answer is simple – we have created the perfect combination of Sentera devices, suitable for storing both types of vegetables for a long time. The only difference can be found in the pre-defined parameters.
According to the “International Food and Agriculture Organisation”, the loss of perishable plant products (fruits, potatoes and vegetables) during storage in the world reaches 20-30 %, not to mention the unnecessary electricity consumption expenses, which come as a result of that.
Sentera’s solutions for climate control
One of the most important stages of vegetable storage is the preparation of the vegetables for long-term storage after their delivery to the warehouse. These are time-consuming and precision-demanding processes, which can be handled best by a Sentera controller, which can receive valuable data from sensors, installed in and outside the warehouse, and as a result, control the indoor environment.
Preparation of potatoes for long-term storage after their delivery to the warehouse
Potatoes, brought to the warehouse, require drying by continuous ventilation with ambient air. The drying time is no longer than 3 days.
After that, the dried potatoes undergo a curing process for 10-15 days, which requires temperature levels of 14-18 ºC and ventilation with ambient air at regular intervals of 4-6 times a day. During this period, superficial damage heals and the skin of the potatoes toughens. At the end of the curing process, the indoor temperature needs to be reduced by 0.5-1.0 ºC per day for no longer than 15 days so the potatoes are cooled enough to be stored successfully.
After that, the dried potatoes undergo a curing process for 10-15 days, which requires temperature levels of 14-18 ºC and ventilation with ambient air at regular intervals of 4-6 times a day. During this period, superficial damage heals and the skin of the potatoes toughens. At the end of the curing process, the indoor temperature needs to be reduced by 0.5-1.0 ºC per day for no longer than 15 days so the potatoes are cooled enough to be stored successfully.
Preparation of onions for long-term storage after their delivery to the warehouse
The first stage of onion storage is keeping the harvested onions at a temperature of 18-25 ºC in order for them to dry. Onions are considered dry when the moisture of their outer layer is 14-16%. The drying time should not exceed 8 days. To prevent neck rot, the onions are then stored at a temperature of 45-47 ºC after the drying stage for 10-12 hours. Lastly, onions should be cooled to 0-4 ºC storage temperature.
Even when the preparation stage is completed, it is still necessary to monitor and control the whole process of ventilation during the entire storage period in order to avoid crop spoilage. A Sentera controller accompanied by sensors can maintain the suitable storage conditions.
The maintenance of an optimal microclimate in a vegetable warehouse requires knowledge and constant responsible work. When managing the microclimate of the vegetable warehouse, we should assess the constantly changing natural conditions and the condition of the stored vegetables. The final condition of the stored vegetables depends highly on those factors. Different types of vegetables react differently to temperature changes. This explains why, after harvesting some perishable products, it is necessary to prepare them for storage immediately under precise conditions. The creation of the required microclimate, in the presence of constantly changing natural conditions, in such vegetable storage facilities is practically impossible without the use of artificial refrigeration devices. In the warm periods of the year, refrigeration systems are necessary when sensitive products that require rapid cooling and low storage temperatures are stored. It is also possible to take advantage of natural cold – when the ambient air cools down naturally and it has a suitable temperature for cooling the stored vegetables. Since a refrigeration system is not used in this case, relatively low energy costs are required to create a microclimate in the warehouse. However, it is sometimes more challenging to maintain the optimal storage temperature of vegetables in early autumn and spring without a refrigeration system since the minimum daily temperature does not fall below 5 °C. Thus, it is rather difficult to maintain the optimal temperature levels effectively since the natural conditions of the environment are constantly changing and the suitable temperature for storage is usually only present in the mornings. Therefore, a ventilation system is the necessity that can provide the optimal conditions for vegetable storage. The storage process can be optimised effectively with the usage of a Sentera controller in combination with Sentera sensors. As a result, the quality of the vegetables will be preserved longer, the losses of stored vegetables due to moisture evaporation will be reduced and the dormancy period of the vegetables will be extended – they start sprouting later in spring – with around 25-30 %.
Sentera's solution measures temperature, humidity and CO2 levels and in potato warehouses, every measured parameter is essential. The environment in the warehouse can be controlled based on the measurements of sensors mounted in and outside the warehouse, which transmit the data to a Sentera controller. In addition, after the controller analyses the data, each external product such as a humidifier, dehumidifier, heater, actuator, etc. receives the necessary command. Why are these three parameters so important?
Carbon dioxide measurement (CO2)Protection against rotting: High levels of carbon dioxide (CO2) can indicate that potatoes are beginning to lack oxygen, which can lead to rotting and growth of harmful microorganisms. Potatoes stay fresh longer when CO2 levels are controlled.
Maintaining quality: The better the conditions in the warehouse, the better the quality of the potatoes. Carbon dioxide levels should be monitored since they can affect the taste and texture of potatoes.
Prevention of fermentation: If there is too much CO2 in the warehouse, it can cause fermentation processes, which will affect negatively the quality and storage time of the potatoes.
Therefore, controlling CO2 levels in potato warehouses is necessary to ensure the quality and longevity of potatoes.
Humidity measurement
Rot prevention: High humidity promotes the growth of rot and mould, which can quickly destroy potatoes. By monitoring the humidity level, measures can be taken to prevent these destructive processes.
Maintaining quality: Optimum moisture levels help maintain the quality of potatoes by preventing them from drying out, shrivelling or becoming too wet, which could affect their taste and texture.
Safety: Excessive moisture can create favourable conditions for harmful bacteria that can be dangerous to health.
In conclusion, humidity measurement is an essential part of the potato storage process, helping to ensure that potatoes remain fresh and intact for a long time.
Temperature measurement
Ensuring the right temperature: The right temperature helps prevent the growth of rotting and harmful microorganisms. Higher temperatures can promote the growth of bacteria and mould, which can lead to storage losses.
Maintaining quality: Potato quality depends on the right storage temperature. On the one hand, if potatoes are stored at high temperature levels, their texture and taste can be affected adversely. In addition, they can soften and sprout. On the other hand, low temperature levels can cause frost damage, making the potatoes inedible.
Long-term storage: Optimal temperature levels allow potatoes to remain fresh and unblemished for a longer time, which is important for both suppliers and consumers.
Dependence on the time of year: Temperature can be affected by the time of year and climatic conditions. By constantly monitoring the temperature level, appropriate measures can be taken to maintain the right conditions.
Prevention of losses: Changes in temperature can lead to faster spoilage of potatoes – they can start to sprout, wither and rot, so temperature measurement and control help reduce financial losses.
Temperature measurement in potato warehouses is an essential factor that reduces the risk of possible losses and ensures potatoes remain fresh and of good quality for a long time.
Sentera can offer you a variety of solutions suitable for vegetable warehouses or tailor one to your needs, as every environment may require a unique combination of devices. We offer solutions for warehouses of various sizes since the Modbus system allows you to create a solution of more than two hundred devices, including controllers, sensors and converters.
What is a potentiometer?
The word potentiometer is on the one hand the name of an electronic component. On the other hand it is also the name for a speed controller for EC motors. In such a speed controller the electronic component is usually used. In both cases, the word 'potentiometer' indicates that something can be adjusted infinitely variable.
Speed controller for EC motors
An EC motor can be seen as the combination of an AC motor with a built-in speed controller (see also the article AC versus EC motors). This built-in speed controller needs information about the desired motor speed. A potentiometer is one of the possibilities to communicate the desired motor speed to the EC motor. That is why a potentiometer is sometimes also described as a speed controller for EC motors. The real speed controller is in fact integrated into the EC motor, while the potentiometer is the device with which the desired speed can be manually set. Using a potentiometer, the speed of an EC motor can be adjusted infinitely variable.
But how does that work? How can the potentiometer inform the EC motor how fast it should turn? Simple: via an electrical signal. In technical jargon, this is called an analogue signal. This means that this electrical signal can be set continuously variable between the minimum and maximum value. The most commonly used analogue signal is 0 to 10 Volt. It can vary between 0 Volt and 10 Volt.
In other words, the potentiometer is a device that translates the position of the rotary knob into an analogue signal (e.g. 0-10 Volt). This analogue signal can be used to control another device. The number of examples is endless, but in the HVAC world analogue signals are widely used to control EC motors, variable speed controllers, valve blade positioning, setting the desired temperature, etc. We will keep on using the example of controlling the EC motor in this article. In this example, the fan would stand still if the control signal is 0 Volt. When the control signal (infinitely variable) increases to 10 Volt, the fan will accelerate (infinitely variable) to the maximum speed, which is reached at 10 Volt.
Different types of analogue signals
In practice, there are many different types of analogue signals, each with their own advantages and disadvantages. The device that is to be controlled by the analogue signal determines which signal type is required. In some cases, there are multiple options.
Here we list the most commonly used analogue signals:
- Voltage signals (e.g. 0-10 Volt): These analogue signals use a different voltage or potential to transmit the information. The EC motor will detect the voltage level of the analogue signal and determine the desired motor speed based on that. This form of analogue signal is very popular because the value of the signal can easily be measured with a Voltmeter. This makes the trouble shooting much easier.
The disadvantage is that the cable length must remain limited. Due to the electrical resistance of cables, there will be a voltage drop with longer cable lengths (10 Volt at the beginning of the cable will no longer be 10 Volt at the end of the cable). This results in lower accuracy. In the example of the EC motor, it will be impossible to reach the maximum fan speed if the analogue signal cable between potentiometer and EC motor is too long. The reason is that the analogue control signal cannot reach it's maximum value of 10 Volt due to the voltage drop in the long cable. - Electrical resistance (e.g. 0 to 10 kΩ): This is the most well-known way to communicate a value in the world of electronics. By the way, a potentiometer is also an electronic component with variable resistance value - more about this later in this article. Back to our example with the EC motor. The EC motor will determine the desired motor speed based on the resistance value of the analogue signal. Here too, a longer cable length between the potentiometer and the EC motor will result in reduced accuracy due to the increasing electrical resistance of the cable. If the cable length between both devices can be kept short, this is a simple and cost-effective solution.
- Current signals (e.g. 4-20 mA): Analogue signals that vary the electrical current to communicate a value. The EC motor will determine the motor speed based on the current of the analogue signal. The more mA detected, the higher the motor speed. In this example, 20 mA corresponds with the maximum motor speed.
The big advantage here is that no accuracy is lost in case of increasing cable length. The increased electrical resistance of the cable will be compensated by the analog signal and the desired current will be achieved. A cable break can also be detected (0 mA can only occur in case of a cable break, since the minimum value of the analogue signal is 4 mA). Detecting possible errors is more complex because current is more difficult to measure than voltage. - Frequency signals (e.g. Pulse-Width Modulation or PWM): This type of analogue signal is also called a pulse train. It is a constant series of pulses with identical amplitude (voltage). The difference is in the frequency and width of the pulses. The EC motor receives a constant series of electrical pulses. The motor speed is determined based on the frequency and duration of the pulses. This form of analog signal is not sensitive to increasing electrical resistance or voltage drops due to longer cable lengths. More advanced electronics are needed to correctly interpret the pulse train and detecting possible errors is also less easy.
In the end, all these analogue signals do the same: they transmit or communicate a certain value between different devices. The difference between these analogue signal types can be seen as communicating the same message in a different language.
In a summary: Voltage signals and electrical resistance are simple and suitable for shorter distances, current and frequency signals are more complex and more suitable for longer distances.
The electronic component 'Potentiometer'
A potentiometer is a three-terminal electronic component that acts as a variable resistor or voltage divider. It consists of a resistive element, a sliding or rotating contact (called a wiper), and three terminals: Two fixed terminals are connected to the ends of the resistive element. One variable terminal (the wiper) slides or rotates along the resistive element to vary the resistance and, consequently, the voltage output.
When a voltage is applied across the two fixed terminals, the wiper divides the voltage based on its position along the resistive element. Moving the wiper changes the resistance in one segment of the circuit while simultaneously altering the resistance in the other segment. This adjusts the voltage between the wiper and one of the fixed terminals.
A potentiometer is often used in an electronic circuit to allow the user to easily adjust a certain value. For example, to set the volume of the radio.
The Sentera product range of potentiometers and control switches
EC fan controllers for continuously variable fan speed control
A potentiometer is typically used to control the speed of EC motors in the HVAC business. That is why it is also referred to as EC fan speed controller or EC fan controllers. The potentiometer generates a control signal (typically 0-10 Volt). This control signal provides information to another device (e.g. fan speed controller). In this example, the potentiometer ‘informs’ the fan speed controller about the requested fan speed via the control signal. An analogue signal can represent a certain value (For example: 8 Volt = 80%). This value lies within a range (0-10 Volt or 0 - 100%). Potentiometers or EC fan speed controllers generate a continuous variable control signal that can be used to define the requested fan speed.
The Sentera product range includes three groups of EC fan speed controllers. These groups are divided according to the supply voltage that the potentiometer needs to function:
1. Low supply voltage
These potentiometers are extremely suitable for combination with EC motors that provide a supply voltage of 10 Volt DC (or similar). It offers the possibility to connect both the supply voltage and the analogue control signal via one cable.
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- SDP-E0US series require a supply voltage in the range of 5 to 24 VDC. The output type can be adjusted by changing the position of a jumper. The minimum and maximum value of the analogue output signal can be adjusted via two trimmers. The jumper and both trimmers can be found behind the front panel of the potentiometer, where the wires are connected.
- SDP-M010 series require a supply voltage of 24 VDC. Via the knob on the front panel, the analogue output signal can be set. If necessary, this knob can be overruled by the Modbus RTU communication. If overruling via Modbus RTU communication is active, the analogue output signal will follow the information in the corresponding Modbus holding register. The knob on the front panel is deactivated during the overruling. Next to adjusting the analogue output signal, all potentiometer settings can be adjusted via Modbus RTU communication. A typical application is to overrule the knob on the front panel during certain moments of the day. For example in a school building. EC fan speed can then be set remotely (via the BMS system or a central computer) while the knob on the front panel is disabled.
- MTP-D010 series require a supply voltage in the range of 3 to 15 VDC. These potentiometers still come in the classic enclosure type. The analogue output signal can be set between 10 % and 100 % of the supplied voltage. E.g. if this potentiometer is connected to a supply voltage of 10 VDC, the analogue output signal can be set in the range of 1 to 10 VDC. If the fan speed is too high at its maximum value, it can be reduced towards 1 to 8 Volt for example.
2. 230 VAC supply voltage
These potentiometers require a supply voltage of 230 VAC. The analogue signal can be connected via a separate cable. Power cables (230 VAC) and control signal cables must always be separated to prevent interference. These potentiometers were developed to generate an analogue signal for devices that do not provide a 10 Volt DC (or similar) supply voltage for the potentiometer.
3. Unpowered potentiometers 10 kOhm
These potentiometers do not require a power supply. They offer a variable resistance value in the range of 0 to 10 kilo Ohms (0 to 10,000 Ohms). This makes it possible to connect these potentiometers with a three wire cable. The only difference between the products in this group is their enclosure.
Control switches for EC motors or damper actuators
These devices regulate EC fan speed in steps. The potentiometers mentioned above generate a continuously variable signal. However, there are certain applications where the user wants to regulate fan speed in a few steps from minimum to maximum, not continuously variable. For these applications, Sentera control switches can be used. Control switches generate a control signal in 3 steps. They divide the analogue 0-10 Volt signal in three (adjustable) steps. This makes it possible to adjust the fan speed in three steps.
Control switches for AC motors with multiple windings
A very specific group of AC motors has a similar operation. These are 3-speed motors that are used in ceiling fans, for example. This group of control switches is designed to control AC motors with 3 separate motor windings. Each winding gives the motor a different speed. When winding one is energized, the motor starts to turn slowly. When winding two is energized, the motor turns a little faster. When the third winding is energized, the motor runs at full speed. To control these type of AC motors, a mechanical switch is needed that connects the 230 VAC supply voltage to one of the three motor windings. Just to be clear, this group of control switches has nothing to do with analogue signals.
What is a building management system and its purpose?
Building Management Systems (BMS), also known as Building Automation Systems (BAS), are computer-based systems installed in buildings to control and monitor the mechanical and electrical equipment of the building, such as HVAC, lighting, energy, fire systems, and security systems. In simple terms, the BMS serves as a central control point for all facilities within a building. Because the BMS can remotely control heating and ventilation systems from a computer or mobile device, facility management staff do not have to physically walk to each building, floor, or room to shut down, switch on, or manually adjust connected devices. Such systems serve to facilitate the operation of cooling or heating systems, support the process of maintaining or developing the many air-conditioning or HVAC systems in commercial and industrial buildings, as well as to create the feeling of comfort in occupants.Main types of BMS systems
HVAC management – Most common parameters such as temperature, relative humidity, CO or CO2, LPG (typically found in enclosed parking garages, due to the engine operation of the vehicles) and air quality must be measured regularly, monitored and configured. But, from a practical point of view, we need the BMS to monitor them remotely due to lack of time or because of our comfort.
Hot water and heating control - Temperature control and pump operations for hot water and central heating are managed by the BMS, assuring proper distribution of water resources.
Lighting control - BM systems automate lighting operations, adjusting for optimal use and energy savings while maintaining comfort and safety standards.
Security systems management - Surveillance and access control are integrated into the BMS, boоsting up building security and quick response to incidents.
How BM systems work?
Building management systems consist of both software and hardware components. A BMS functions by collecting information from connected devices and equipment (configuration tools, gateways, sensors, fan speed controllers and etc.) within a building, processing all this data centrally and then sending different commands to control various building systems or even single devices. This is done according to set criteria and user inputs, using a network of the connected hardware and software components. The main functionalities of a standard BM system are:
Data collection for environmental conditions and parameters from temperature, humidity or even differential pressure sensors and occupancy detectors that gather real-time data on different environmental conditions.
Control process - Devices such as valves and dampers that physically adjust system components based on control signals from the automation layer.
To establish communication - Sends collected data or automacially update software of the connected devices to the automation layer via hardwired connections or Ethernet.
Feedback - Provides real-time feedback on the status and performance of various systems or single devices in a room.
Components of the BMS system
Software - The software component of a BMS is critical for integrating the data collected from various sensors in different fans or ventilation modules and executing the control strategies.
Controllers - Within the control panels, controllers hold the strategic logic used to manage the subsystems of the building effectively. These controllers are programmed to respond to the data received from sensors, adjusting the building's systems to maintain optimal environmental conditions. Sentera’s wide range of smart sensors and sensor controllers for every environmental parameter measurement and control, could be directly connected to a standard BM system and, yet, act on their own.
User interface - The user interface allows facility managers and building operators to interact with the system, monitor real-time data and make adjustments as needed. This interface can be accessed through web-based portals, mobile applications, or directly through physical interfaces on the control panels.
Communication system - In the context of a Building Management System (BMS), the network infrastructure refers to the system of connections that allow data to be communicated between the various components of the BMS such as sensors, control panels, actuators, and the user interface.
Connecting the system to every componentWired network - Wired networks involve physical cables (e.g., Ethernet cables) that connect devices within the BMS. These cables transmit data between sensors, actuators, control panels, and other components.
Wireless network - Wireless networks are Wi-Fi, Zigbee, or Bluetooth.
Protocols - In networking terms, a protocol is a standard or set of rules that devices must follow to communicate effectively over a network. Protocols like BACnet and Modbus (most common in HVAC industry) define data structure, method of data exchange and timing for communication. This enables different systems and devices within a BMS to exchange information reliably and interpret it correctly, ensuring seamless operation of building management functions.
Advantages of Implementing a BMS
Implementing a modern Building Management System (BMS) provides significant advantages that contribute to operational efficiencies, safety, and occupant comfort. Here is a closer look at how a BMS enhances building management:
Energy efficiency - A modern BMS optimizes the operation of mechanical and electrical systems including HVAC, lighting, and power systems. By automating processes such as turning off lights when not needed and adjusting temperature based on occupancy, a BMS can significantly reduce energy consumption and lower energy bills.
Comfort - By maintaining controlled indoor environmental conditions—regulating temperature, humidity, and air quality a BMS ensures a comfortable atmosphere for occupants. Appropriate lighting levels and smooth operation of systems contribute to an environment conducive to productivity and well-being.
Safety and emergency response - By integrating fire alarms, smoke detectors and other emergency systems, the system can immediately detect and respond to emergencies.
Reduced operating costs - Through efficient management of building systems, a BMS reduces the costs associated with maintenance and operation. It extends the lifespan of equipment by preventing overuse and facilitating timely maintenance, thereby decreasing the likelihood of costly repairs or replacements.
Application field of BMS systems
The most common types of application fields of building management systems are lightning and electric power control, HVAC industry, security and observation, access control, fire and alarm systems, lifts, elevators and etc., plumbing industry.
Sentera’s solutions
Through the years, the Sentera Controls company has declared itself for measuring and monitoring life-changing parameters in the whole industry. We started as a producer of smart devices and proceeded with effective control solutions for your HVAC system. Our devices (HVAC sensors, electronic or transformer fan speed controller, potentiometers, gateways or configuring devices and other), including our wide branch of effective, easy to install and use, full pack solutions are made for installing, monitoring and configuring HVAC installations. Every solution of Sentera (which includes a suitable for the solution product like room sensor, transformer fan speed controller or Internet gateway) could be connected to a BM system in order to easily monitor and configure every environmental parameters and take on-time actions to fix the occurring problems and restore the comfort of occupants.
Sentera’s solutions for:
Fan speed control – In these types of solutions, the main devices (the fan speed controller) must regulate the fan speed in order to supply enough fresh air and extract the stale air. The air flow volume can be adjusted manually or automatically according to the stale. In case you want to do it manually, the fan speed can be adjusted via a switch or potentiometer, despite that we suggest you use the remote fan speed control solutions for your comfort. For automatic fan speed control, an HVAC sensor should be connected to the AC fan speed controller or directly to the EC fan.
Control an air curtain - Air curtains can be activated manually or automatically, based on temperature difference in the rooms. In manual control mode, the air velocity can be adjusted via a switch or potentiometer. This can be done locally or remotely. For automatic control mode, temperature sensors measure the difference between the inside and outside temperature and activate the air curtain if necessary.
Destratification control - Destratification units or ceiling fans balance the air temperature nearby the ceiling and at the floor level. These fans are often used in large halls with high ceilings (for example: production halls, warehouses, museums and others) to reduce heating costs by preventing large temperature differences between floor and ceiling level. Destratification controllers measure temperatures at ceiling and floor levels to optimise fan speed based on the temperature difference.
Fan heater or cooler control - Electric or water-supplied fan heaters / coolers are typically used in logistics, production halls or sports facilities to heat or cool the air. Fan speed can be controlled manually or on demand. This leads to immediate energy and financial cost savings and reduces health issues, as it creates the most suitable air quality and temperature levels for the occupants.
Visit our website, see our wide variety of different products, suitable for you, your health and your comfort, choose a proper solution and take control of your environment. With our help, you manage to create the perfect air quality in the building. By simply connecting a whole BM system you can remotely control the system (-s) in your facility and get notified in case of faulty operations or occurred problems with environmental parameters, which are crucial to be maintained on-time. For more, click on www.sentera.eu and follow us on every social media platform to be in touch with eventual updates or new products.
What is a TRIAC technology for fan speed control? A TRIAC is a three-terminal AC switch that can regulate AC loads at high voltage, unlike other silicon controlled rectifiers. It can show whether the applied gate signal is positive or negative. The gate is connected to both the N (neutral) and P (positive) regions, transferring a gate signal regardless of polarity. Unlike other devices, it does not have an anode and cathode (because, during an operation, they switch places: the anode becomes a cathode and backwards) and it has three terminals: main terminal 1 (MT1), main terminal 2 (MT2) and gate terminal (G). The TRIACs can be activated by applying a gate voltage higher than the break over voltage. Alternatively, it can be turned on by a 35-microsecond gate pulse.
How do TRIACs work?
The TRIACs principle of operation is often compared to two thyristors working in antiparallel, but the construction of TRIAC devices describes how they can perform a switching function over both parts of the AC waveform. This means, unlike standard thyristors, TRIACs can work with the current flowing in either direction so only one device needs to be used for many applications. It also means the device can perform conduction whether the polarity sent through the terminals is positive or negative. However, the sensitivity of the current required to trigger the device is highest when both terminals are with the same type of polarity.
As such, the four triggering modes of operation are defined as follows:
- I+ Mode: Terminal 2 current is +ve (positive), gate current is +ve
- I- Mode: Terminal 2 current is +ve, gate current is –ve (negative)
- II+ Mode: Terminal 2 current is -ve, gate current is +ve
- II- Mode: Terminal 2 current is -ve, gate current is -ve
Area of use
TRIACs are utilized in a wide range of applications, including light dimmers, speed controls for fans and other electric motors, and sophisticated computerized control circuits in a wide range of home small and large appliances. They may be used in both AC and DC circuits, but their initial purpose was to replace the need for two SCRs in AC circuits.
Typical, common application fields are:
- As a switching circuit – if the first switch is open, the device (with TRIACs) acts as an open switch.
- Fan speed control – TRIACs are often used in devices for AC fan speed control in AC circuits.
- Phase-controlled power delivery – they can control power delivery to various AC loads by adjusting the phase angle.
- Temperature control systems – TRIACs can be integrated in thermostats and heating control systems in order to help the process of regulating the temperature by adjusting the power delivered to heating pumps, duct, etc.
- To minimise the electrical noise – TRIACs can operate without mechanical movement, reducing the electrical noise, coming from the motor.
Sentera’s devices with TRIAC technology for fan speed control
Through the years, Sentera has developed many practical and innovative devices to ease the fan speed control in your house, factory, warehouse, etc. Our mission is to help our customer manage their heating and cooling or ventilation systems from a distance and, thus, to create ideal and healthy indoor environment, which leads to preserving physical structure of the body and mental health. In addition, we created different products, which could be integrated in whole installations or systems or operate by themselves – from typical sensors and sensor controllers to potentiometers, Internet gateways, transformer, variable or even electric fan speed controllers and etc. Most of our devices use the TRIAC technology of fan speed control, since this is a universal, yet innovative method for safe and precise speed regulation. Let us see these products:- AH2C1-6 series – The series feature electric heating controllers for single-phase or two-phase electric heating. The current is TRIAC-switched, which minimises wear and tear, while enhanced control accuracy reduces energy costs. Use the AH2A1-6 expansion module from the series to develop a reliable HVAC installation for your needs!
- DRE – This is an electronic fan speed controller, suitable for DIN rail mounting in electrical cabinets, featuring both regulated and unregulated output and perfect to control the speed of single-phase voltage controllable motors. All parameters are accessible via Modbus RTU communication protocol.
- DRX/Y series – The series includes electronic fan speed controllers for AC fans, suitable for DIN rail mounting with Modbus RTU communication.
- ECMF8 – This is an HVAC controller for EC fans or variable fan speed controllers. The device could be used as a single or dual ventilation control, as it requires a specific firmware, which you can download via SenteraWeb.
- EVS/S series – The EVS/-S series features AC fan speed controllers for single-phase voltage controllable motors and Modbus RTU communication.
- GTE*DM series - The GTE controller automatically regulates the speed of single-phase voltage controllable motors, according to the measured temperature values and features a Modbus RTU communication.
- GTE*DT series - The GTE controller automatically regulates the speed of single-phase voltage controllable motors, according to the measured temperature values and it has an integrated Schuko socket for motor connection and a PT500 probe input.
- GTEE1 series – These controllers automatically regulate the speed of single-phase voltage controllable motors according to the measured temperature values and controls a heater according to a temperature set point.
- GTT series - The series feature transformer fan speed controllers used to regulate the speed of single-phase voltage controllable motors in automatic or manual mode (in five steps) according to the temperature by varying the output voltage according to the measured temperature.
- ITR/S – These electronic fan speed controllers regulate the speed of single-phase voltage controllable motors by varying the supplied voltage. They feature an internal trimmer for minimum speed adjustment and an unregulated output for valve, lamp or damper connection.
- LTV – This potentiometer provides a stepless output signal to control fans with EC motors and it is used as an in-put device for controllers.
- LTX/-Y – These controllers provide an option for manual regulation of the speed of single-phase, voltage controllable motors (EC) by varying the supply voltage through phase-angle control.
- MTP – The purpose of MTP is to regulate the speed of standard fans with EC motors and provide an infinitely variable output signal between two internally selectable positions: Vmin and Vmax.
- MTV – These potentiometers are used to provide a stepless output signal for fan speed control.
- MTX/-Y – The MTX and MTY series of TRIAC-based variable fan speed controllers are used to regulate the speed of voltage controllable motor manually through phase angle control.
- MVS/S – Both series feature electronic fan speed controllers, suitable for DIN rail mounting. They feature a Modbus RTU communication, option for remote control, adjustable OFF level, minimum and maximum speed adjustment and time-limited motor operation.
- RDCZ9 – HVAC controllers for regulating the fan speed of AC voltage controllable fans, lighting systems and other. They feature a wide supply voltage range and a variable control output signal between an adjustable minimum and maximum level.
- RTR – These are transformer fan speed controllers that regulate the speed of single-phase voltage controllable motors by varying the output voltage in steps.
- RTVS8 – The series features transformer fan speed controllers for single-phase voltage controllable motors. They regulate the speed of the fan in five steps by varying the output voltage.
- SC2/A – Fan speed controllers with day or night operating mode. They are intended for single-phase voltage controllable motors. The SC2A1 series has external TK monitoring, while the SC2 – does not.
- SD* -DT – Series of AC fan speed controllers for manual regulation of the speed from low to high (SDY) and from high to low (SDX). The devices in this series are suitable for surface and inset mounting and use TRIAC technology of regulating fan speed.
- SDP – Intended for precise regulation of the speed of standard EC fans, damper actuator, AC fan speed controllers and frequency inverters. Suitable for a variety of applications where a variable control signal is required.
- SER-1 series – These fan speed controllers can regulate the speed of single-phase voltage controllable motors by adjusting the output voltage only in five steps. They also feature an emergency button for smoke extraction.
- SFPR1 series – These transformer speed controllers are intended for precise regulation of the speed of single-phase voltage controllable motors, as they adjust the output voltage. They feature TK monitoring for thermal motor protection and an input for remote start/stop.
- ST2R – Two-speed transformer controllers for single-phase voltage controllable motors. The devices are equipped with autotransformers, built-in clock, digital timer and a LCD display.
- STRA1 and STR1 series of fan speed controllers are intended for manual control of single-phase voltage controllable AC fans. The devices of the STRA1 series have an external TK function.
- STRS1 - 5-step transformer fan speed controller for single-phase motors. The fan speed can be adjusted using the rotary switch on the front cover and the series features a TK monitoring.
- STTA – The series features transformer fan speed controllers, intended for single-phase voltage controllable motors. They vary the output voltage and control the speed in five steps.
- STVS1 and STVS4 series – 5 step fan speed controllers, intended for single- or three-phase voltage controllable motors. They are equipped with autotransformers and feature TK monitoring for thermal motor protection.
- TVSS5 - The devices in this series control the speed of three-phase voltage controllable electric motors via an input control signal. They have Modbus RTU communication and thermal contacts to provide overheating protection of motors.
In conclusion, the TRIAC fan speed control technology remains the best choice for a precise control of the speed, as in the same time protects the motor from overheating and wear out of the components of the motor. For easy remote monitoring and control of the connected devices, you can use your own created HVAC installation on the Sentera cloud platform – SenteraWeb. Subscribe to our social media platform for more news: