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3-step control switch for EC fans | no OFF position

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Article code SMTND-3P-AL
Intrastat number 85.36.50.15
Category Control switches for EC motors or damper actuators
Current stock 0 U
Factory lead time 5 Day(s)
Next arrival 06/11/2026 - 60 U

Product description

This is a 3-step control switch designed to optimise control of EC fan speed, damper actuators, AC fan speed controllers or frequency inverters. The SMTND-3P-AL offers versatile control, providing three fixed positions that simplify the process of adjusting fan speed. These fixed positions ensure effortless optimisation, allowing you to easily find the ideal speed for your specific ventilation requirements.

It features adjustable output signals. Positions 1 and 2 offer the flexibility to customise output signals within the 1—10 VDC range, while position 3 consistently delivers the full input voltage of 10 VDC.

The SMTND-3P-AL comes without an OFF position. No need to worry about inadvertently turning off your system; with the SMTND-3P-AL, it is all about reliability and consistent performance.

Designed with durability in mind, the splashproof enclosure of the SMTND-3P-AL allows for either inset (IP44) or surface mounting (IP54). This ensures that, regardless of the preferred installation method, the device remains robust enough to withstand various environmental factors.

Additional specifications and description

What Is an EC Motor and Why Is It Better Than an AC Motor?
An Electronically Commutated (EC) motor generally features a rotor composed of permanent magnets that rotates within or around the stator. The integrated fan speed controller produces an electrical current within the stator windings, its strength varying based on the 0—10 V control signal. This electrical current generates a rotating magnetic field, to which the permanent magnets align, thereby propelling the operation of the EC motor.
The main advantages of EC motors over AC motors are higher energy efficiency, long service life, lower noise levels, lower electromagnetic interference (EMI). 
For optimal functionality, an EC motor relies on a control signal that specifies the desired fan speed. This control signal can be digital, employing Modbus RTU communication, or analogue, typically ranging from 0 to 10 Volts. The SMTND-3P-AL manually produces such a signal in stepped increments. 

What Is a 3-Step Control Switch?
The output voltage of this control switch varies according to the position of the rotary knob. The output voltage is divided in three steps. This control switch controls EC fans or damper actuators in three steps. It can also remotely control AC fan speed controllers (for instance Sentera’s EVS or MVS series) or frequency inverters (FI-E series) in three steps. This control switch can be installed in the living room while the fan speed controller is located in a technical room or an electrical cabinet.

How Can the Control Signal Be Adjusted?
For some applications, it is desirable to adjust the control signal in order to obtain the optimal fan speed. The control signal of position 1 and position 2 can be adjusted, while the signal of position 3 is fixed. For the adjustable positions, the SMTND-3P-AL features internal trimmers to set the signal within the range from 1 to 10 VDC. Position 3 is always equal to the supply voltage, i.e. 10 VDC.
 
 EC fan control switch 3 posIn some occasions, it is technically or legally required to ensure a minimum air supply in all circumstances. The fan speed must never drop below a minimum level. Since this control switch does not have an OFF position, the control signal will never reach 0 V. Even in position 1, the control signal will be minimum 1 VDC (this minimum output voltage can be adjusted via the built-in trimmer.)

What Makes the Enclosure Reliable?
The SMTND-3P-AL enclosure is made of solid white ASA plastic that is UV resistant and protects the electronics from dust, water and impacts. The enclosure features both flush and wall mounting options, making it easy to install in any kind of wall, including drywalls, masonry walls or panels. You do not need to look for different product versions. If you choose the flush mounting option, it fits perfectly into the standard European box and blends in with the background. The protection class is IP44 for flush and IP54 for surface mounting. It looks nice and is a good match for any interior style. It is very easy to clean using only a damp cloth.
Our manual control switch is designed to be durable and reliable in diverse HVAC applications. It features a robust build that can withstand the demands of continuous operation, providing users with a dependable solution for their fan control needs.

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