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NOT FOR SALE YET - Temperature-based control | AC fans | recirculation

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Article code AH-D-000010
Current stock 1 U.
Factory lead time 4 Week(s)

Solution description

Cutting-edge temperature-based control system for recirculation air handling unit. The system features two AC fans equipped with frequency inverters, designed to operate on a 3-phase 400 V power supply, with a power rating of 4 kW and a maximum current of 9,5 A. The AHU incorporates a recirculation chamber with an actuator-controlled damper. It also includes a water heater complete with a pump and a valve. The heater is equipped with frost protection mechanisms, ensuring reliable operation even in freezing conditions. To provide effective cooling, the AHU integrates a water cooler with a chiller and a responsive 3-way valve. To maintain optimal system performance, our solution includes filter clogging control and fan operation control through pressure sensors. Additionally, our system offers comprehensive control over the supply and exhaust dampers, enabling precise airflow management and ventilation control.

Additional specifications and description

This solution is designed to monitor and control air handling unit that is shown on schematic below:
Recirculation AHU schematics with numeration of specific parts

Air handling unit consists of eight parts, which are: supply (1), exhaust (8) and recirculation (2) air dampers; supply air filter (3); supply (4) and exhaust (7) fans; air heater (5) and air cooler (6).


Control logic description

This solution is designed to ensure fully automatic operation of the AHU. The operating mode is determined by sensor readings. The HVAC controller DRPUM has built-in predefined logics for different AHU parts.

To ensure optimal performance and prevent potential damage to the air dampers, the supply and exhaust air dampers open 30 seconds prior to the activation of the supply and exhaust fans. This is particularly crucial for high air flow AHUs.


The condition of the air filter is measured via a differential pressure transmitter HPS-M-1K0-2. The measurements are transferred to DRPUM (master device). If the pressure drop on the filter exceeds the setpoint, the user will receive a notification to perform maintenance. However, the AHU continues its operation regardless of how clogged the filter is.


The supply and exhaust fan speed can be controlled either manually or automatically via frequency inverters FI-E-44095E2. Dual differential pressure transmitter HPD-G-1K0 is also used to control fan operation. In case of mechanical failure (jamming, bearing breakdown), there will be no pressure drop and the master device will take the following steps: switch off frequency inverters, close air dampers, and inform the user about the error. In automatic mode HPD-G-1K0 can be used to maintain a specific pressure difference.


Additionally, this solution includes a recirculation system, consisting of three actuator-controlled air dampers: supply, exhaust and recirculation. Users can choose from two different control options. The first option utilizes duct temperature and humidity sensor DSTHM-2, which is installed inside the mixing chamber. The position of dampers is defined by the desired air temperature in the mixing chamber. The second option implies manual input of the required damper positions. In this mode, DSTHM-2 monitors the resulting temperature. The recirculation system can be utilized both during cold and warm periods of the year and can be easily deactivated by closing the recirculation damper.


The air heater operation is regulated using a duct temperature and humidity sensor DSTHM-2. If the measured temperature is higher than the desired one, the 3-way valve starts to close, reducing the amount of hot water supplied to the air heater. Conversely, if the measured temperature falls below the desired value, the 3-way valve gradually opens. The pump maintains a constant speed at all time to ensure hydraulic regime.


The air heater has two types of frost protection: air and water. Air frost protection is provided with a special relay - frost protection thermostat. It is placed directly after the heater and used to measure temperature. If the measured value drops below adjustable setpoint, the following sequence occurs:
  • Both supply and exhaust fans stop, air dampers close;
  • The 3-way valve fully opens;
  • When the air temperature after the heater exceeds the setpoint, dampers and fans resume their normal operation.
Water frost protection is ensured by using a temperature sensor for fluid pipes DTP-M. It should be installed on the return water pipe at the exit from the air heater. If the measured water temperature drops below 25°C (this setpoint can be changed), the following scenario will occur:
  • Both supply and exhaust fans stop, air dampers close;
  • The 3-way valve fully opens;
  • When the water temperature after heater surpasses 25°C, dampers and fans will resume their normal operation.
The air cooler operation relies on measurements given by the room temperature and humidity sensor RSTHM-2. If the actual temperature is higher than the desired value, the 3-way valve opens to supply the air cooler with cold water. The valve position depends on the temperature differential – the hotter the room, the wider the valve opens. Duct temperature sensors are not used to control the air cooler due to the fact that air can warm up while passing through the fan and ducts.

System configuration

This solution includes a network gateway DIG-M-2. It provides the user with access to the online HVAC platform – SenteraWeb. The connection can be established via an Ethernet cable or a Wi-Fi network. It allows remote monitoring of data and adjustment of settings for the connected HVAC devices via the internet. Data logging is also supported.

Components of this solution

Article code
Quantity
Description

DRPUM

1 U.

The DRPUM is a universal HVAC controller engineered for efficiency and flexibility, which seamlessly integrates into your HVAC setup. It features RJ45 and RJ12 sockets for connecting Modbus RTU slave devices. A single network cable distributes both supply voltage and Modbus RTU communication across your entire network of devices. There are two Modbus channels - one dedicated to linking with a Building Management System or SenteraWeb Cloud services, and another to connect up to 247 slave devices. The DRPUM is delivered without pre-installed firmware, but you can download the appropriate firmware according to your application. The device is compact and efficient, its enclosure is DIN rail mounted providing easy mounting and neat organization of your HVAC control system.

DRPS8-24-40

1 U.

A 24-volt switched-mode power supply (SMPS) is a type of electronic power supply that converts electrical energy from one voltage level to another. This supply module with the convenience of DIN rail mounting is a versatile solution for various applications across different industries. Whether you're managing automation systems (e.g. heating or ventilation systems), control panels, or electronic devices, this power supply is the key to your reliable and secure operation. 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. Because it is designed to be mounted on a DIN rail, integrating the power supply into your electrical cabinet will be simpler. The device is shielded from dust and dirt by the IP20 protection provided by the enclosure. In addition, the safety of your electrical installation is increased by the overload and overvoltage protection. Comparing to linear power supplies, switching power supplies are more efficient, lighter, and more compact (due to their transformer-free design). Because of their high efficiency, they produce less heat and contribute to greater energy savings.

SATD1-24-63

1 U.

A galvanically isolated transformer is a device that provides electrical isolation between two or more electrical circuits. Transformers that are galvanically isolated have an extra layer of insulation that guarantees total segregation between the primary and secondary sides. This isolation provides a high level of safety and protection for connected equipment by preventing the transfer of electrical noise or voltage spikes. This single-phase safety transformer provides safe electrical isolation between the primary (input) voltage of 230 VAC and secondary (output) voltage of 24 VAC. The built-in PTC in the primary winding detects overloads and short circuits and disables the transformer to prevent an overheating. The apparent power capacity of the transformer is 63 VA (volt-ampere). Transformers with galvanic isolation have multiple applications in diverse industries. Medical equipment, industrial control systems, renewable energy systems, and audio equipment are a few of the major applications. The enclosure can be installed in an electrical cabinet on a standard DIN rail. The transformer offers IP30 protection against moisture and dust.

DMDBM22

3 U.

This 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.

ODTHM

1 U.

Outdoor temperature and humidity sensor for HVAC applications. The power supply voltage is 24 V DC PoM, which means that Modbus RTU communication and a 24 V DC power supply can be connected using a single RJ45 connector. The sensor measures temperature, relative humidity, and the amount of light in the environment. It is suitable for use in harsh environments or in outdoor applications. Modbus RTU communication is used to transmit the measured values and it allows you to change all of the settings. The ambient light sensor can be used in many applications to control the ventilation system based on the occupancy of the room.

RSTHM-2

1 U.

Temperature, relative humidity, and ambient light level are measured by this HVAC room sensor. The dew point is calculated using the measured values of temperature and relative humidity. The power supply is 24 V DC PoM. This means that one RJ45 connector can connect Modbus RTU communication and a 24 V DC power supply. Modbus RTU communication is used to transmit the measured values. The ambient light sensor can be used in many applications to control the ventilation system based on the occupancy of the room. Modbus RTU can be used to change all of the settings. The light intensity of the LEDs used for status indication can also be adjusted.

HPD-G-1K0

1 U.

The HPD series offers the capability to simultaneously measure differential pressure in two distinct locations. It requires 24 VDC or 24 VAC supply voltage and its operational range is from 0 to 1.000 Pa. Based on the K-factor of the fan, air volume flow is calculated. Air velocity readout is available by connecting external Pitot tube connection set. Transmitting measured values realised through two output channels and Modbus RTU connectivity. The output type is selectable: 0-10 VDC, 0-20 mA or 0-100% PWM. All parameters are adjustable via Modbus RTU, enhancing customization and adaptability to specific requirements. One of the primary applications of the HPD series is monitoring the volume of supplied and extracted air in ventilation systems or Air Handling Units. Its surface-mountable enclosure has an IP65 rating, safeguarding against the ingress of dust and moisture, thus ensuring reliable performance in various environmental conditions.

HPS-M-1K0 -2

1 U.

This HVAC sensor measures differential pressure within the range from 0 to 1.000 Pa and operates with a supply voltage of 24 VDC, Power over Modbus or PoM – both Modbus RTU communication and power supply are connected via the RJ45 socket using a single cable. This sensor can also measure air volume flow or air velocity. The measured value is available via Modbus RTU communication. The four LED indicators provide a visual indication of the sensor status and the measured values. The differential pressure range and all other settings are adjusted via Modbus RTU.

DSTHM-2

1 U.

This HVAC transmitter measures temperature and relative humidity in air ducts. The dew point is calculated using the measured values. The power supply is 24 V DC PoM. This means that one RJ45 connector can connect Modbus RTU communication and a 24 V DC power supply. The sensor makes use of Modbus RTU communication to transmit the measured values. It can also be used to change several other the settings.

DSTHM-2

1 U.

This HVAC transmitter measures temperature and relative humidity in air ducts. The dew point is calculated using the measured values. The power supply is 24 V DC PoM. This means that one RJ45 connector can connect Modbus RTU communication and a 24 V DC power supply. The sensor makes use of Modbus RTU communication to transmit the measured values. It can also be used to change several other the settings.

DTP-M

1 U.

This sensor measures the temperature of water pipes. It is mounted directly onto the water pipe thus eliminating the risk of corrosion and leaks, without impacting the flow rates. The copper plate is a temperature conductor that registers the temperature of the pipe. The temperature of the pipe is a good indicator of the water temperature inside. The measured temperature is transmitted via Modbus RTU. The supply voltage is 24 VDC - both power supply and Modbus RTU communication are connected via the RJ45 connector.

DIG-M-2

1 U.

The DIG-M-2 Gateway is designed to connect Sentera devices to the SenteraWeb online HVAC platform. It provides a means of communication between the devices and the platform, allowing remote monitoring, data logging and adjustment of settings via the internet. The gateway can be connected to the Sentera devices using either an Ethernet cable or a Wi-Fi network. It is equipped with an RJ45 connector, which serves as a connection point for both Modbus RTU communication and the 24 VDC supply voltage. This enables the devices to communicate with the gateway and receive power from it. Once connected to the SenteraWeb platform, the gateway enables remote access and control of the connected HVAC devices. Users can monitor data, such as temperature, humidity and other relevant parameters, and make adjustments to the settings as needed. The platform also supports data logging, allowing for historical data analysis and system optimization. The gateway is designed to be mounted on a DIN rail. This allows for easy installation and integration into existing setups.

DRM-M-02

1 U.

The DRM-M-02 are relay output modules for Modbus networks. They are equipped with 2 C/O relays with a normally open and normally closed contact. The relay status can be controlled via the Modbus RTU registers. Each relay has a switching capacity of 5 A (resistive) at a voltage of 220 VDC / 250 VAC. The device is designed for mounting on a DIN rail and is powered with 24 VDC, Power over Modbus via an RJ45 connection for both Modbus RTU data exchange and supply voltage running over one UTP cable.

FI-E44095E2

1 U.

Variable speed drive to control 3ph 400 Volt motors. This VSD is particularly simple to use. For most applications it is not necessary to change the default settings. That is why this variable speed drive is ideal for controlling fans and pumps in HVAC applications. The required supply voltage is three-phase 400 Volt. Various types of three-phase 400 Volt motors can be controlled: IE3 or IE4 induction motors, permanent magnet motors, brushless DC or synchronous reluctance motors. One or multiple motors with a (combined) maximum current of 9.5 A can be controlled by this drive. Motor speed can be set via the intuitive keypad or via the inputs. Configuration is simplified via 14 basic parameters and application macro functions. The enclosure can be DIN rail mounted in an electrical cabinet. It offers an IP20 protection against ingress of dust. The integrated EMC filter is Class C1. Manufacturers code: ODE-3-240095-3F42

FI-E44095E2

1 U.

Variable speed drive to control 3ph 400 Volt motors. This VSD is particularly simple to use. For most applications it is not necessary to change the default settings. That is why this variable speed drive is ideal for controlling fans and pumps in HVAC applications. The required supply voltage is three-phase 400 Volt. Various types of three-phase 400 Volt motors can be controlled: IE3 or IE4 induction motors, permanent magnet motors, brushless DC or synchronous reluctance motors. One or multiple motors with a (combined) maximum current of 9.5 A can be controlled by this drive. Motor speed can be set via the intuitive keypad or via the inputs. Configuration is simplified via 14 basic parameters and application macro functions. The enclosure can be DIN rail mounted in an electrical cabinet. It offers an IP20 protection against ingress of dust. The integrated EMC filter is Class C1. Manufacturers code: ODE-3-240095-3F42

ADPT-3SM-FI

2 U.

Adapter to connect Invertek frequency inverter (FI-E and FISE series) to a Sentera Modbus RTU network. The Invertek RS485 communication is converted into Modbus RTU communication. This makes it possible for the Sentera HVAC controllers to control the Invertek frequency inverters via Modbus RTU. One integrated control solution for your HVAC or ventilation system.

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