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Fan speed controller 400 V | TK monitoring | remote run-stop | 1,5 A

Article code STRA4-15L40
GTIN 0.540.100.301.593.3
Intrastat number
Category Advanced AC fan speed control - TK monitoring
Current stock 1 U.
Factory lead time 5 Day(s)

Product description

STRA4 is a 5-step fan speed controller designed specifically for 3-phase 400 V motors equipped with thermal contacts. Its maximum combined motor current of 1,5 A.

Fan speed is adjusted using a rotary switch with an OFF position. The motor can be enabled or disabled remotely using digital inputs.

To ensure motor safety, STRA4 incorporates a TK monitoring function. In the event of overheating, the TK monitoring function automatically deactivates the motor, preventing damage.
In cases of power failure, the STRA4 has an automatic restart feature. After a power outage, the motor will restart automatically without any manual intervention.

STRA4 includes an alarm output and an unregulated output. The alarm output can be used to trigger external devices to generate alarms. The unregulated output can control external devices to confirm normal operation or activate additional equipment.

Fan speed is regulated by reducing the motor voltage using autotransformers. This technology ensures that the output voltage has a perfect sinusoidal shape, guaranteeing quiet operation of the motor and minimizing electrical noise.

The enclosure of the STRA4 is designed for surface mounting and offers IP54 protection. This protection ensures resistance against the ingress of dirt, dust, and moisture.

Additional specifications and description

General information
The STRA4 transformer controller is designed to work with three-phase electric motors with a supply voltage of 400 V, whose maximum current does not exceed 1,5 A. The fan speed is adjusted using a switch located on the housing. The switch has five steps to control the voltage, as well as an OFF position. Using digital inputs to connect a switch or relay, it is possible to remotely start and stop the motor. Additional features of the controller  include the presence of terminals for connecting thermal contacts and the ability to automatically restart in the event of a power failure. The speed controller housing provides IP54 protection.

Why a transformer speed controller?
Most electric motors are controlled by regulating the voltage supplied to them. Transformer controllers are a simple, convenient and cost-effective solution for speed control. An important advantage of using these devices is that they do not create electromagnetic disturbances that can negatively affect the operation of the electric motor and other nearby electrical equipment. Transformer speed controllers are the best option for use in rooms and areas with increased requirements for noise levels. Thus, the transformer speed controller is a solution that will ensure reliable and quiet operation of the electric motor at an affordable price.STRA4 transformer controller

Remotely controlled start and stop

The STRA4 transformer speed controller has one normally open and one normally closed contact. They can be used to remotely turn the controller on and off, as well as to monitor its operation. Indication and warning devices, thermostats, temperature relays, etc. are used as connected equipment.

Unregulated output
The STRA4 speed controller is equipped with an additional unregulated output (230 V), which is closed when the electric motor is running. It is called unregulated because it has only two positions - closed (230 V) and open (0 V). The current for this output should not exceed 2 A. One example of the use of this output is to control the electric drive of an air or water valve. When the fan is turned on, the valve opens, and when it is turned off, it closes. If you need to remotely monitor the operation of the transformer controller, you can connect a lamp to the unregulated output.

Motor overheat protection
The STRA4 fan speed controller is equipped with terminals for connecting the thermal contacts of the electric motor (TK). Thermal contacts are used to measure the temperature on the motor windings. In case of overheating, the electric motor will be stopped to eliminate the risk of its failure. If the motor is not equipped with thermal contacts, the TK terminals must be connected via bridge to simulate normal operation.


The STRA4 speed controller is equipped with an unregulated output (230 V), which notifies of an accident. It is triggered when the thermal contacts that protect the electric motor from overheating open. This output can be used to connect a lamp or a buzzer. The maximum current of the connected equipment should not exceed 1 A.

Automatic power-on after power failure

When working with electrical equipment, you should always be aware of possible power failures. In the event of such a failure, once power is restored, the speed controller and motor will restart automatically.

LED indication
The STRA4 fan speed controller is equipped with LED indicators located on the front of the controller. When connecting power to the transformer controller, the indicator will light green. When the motor overheat protection is triggered, the red indicator will light up.

The main purpose of the housing is to protect the inside of the controller from external contaminants and moisture, as well as from adverse environmental factors. Sentera closely monitors the quality of its manufactured and supplied products. The housing of STRA4 is made of sheet steel with a protective paint coating and provides reliable protection against mechanical and other influences. It is certified according to the European standard EN 62208 and has a dust and moisture protection rating of IP54. To ensure maximum reliable and safe operation, as well as to eliminate the possibility of overheating, the controller must be installed in a cool place without direct sunlight. The ambient temperature for operating the transformer speed controller must be in the range from -20 to +35 °C, and the relative humidity - from 5 to 95%. Moisture condensation in the work area is not allowed.

Remarks, reviews & ratings

The controller works well, easy to install, not noisy.
Regulator spełnia moje oczekiwania, łatwy do podłączenia, zgodny z opisem, polecam
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