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  • New item   -99.76€Transformer fan motor speed controller with automatic restart | TK | 5A | 230VAC | surface-mounted | IP54 | Sentera Controls | STRA1-50L22
    New item   -99.76€Transformer fan motor speed controller with automatic restart | TK | 5A | 230VAC | surface-mounted | IP54 | Sentera Controls | STRA1-50L22 1
    New item   -99.76€Transformer fan motor speed controller with automatic restart | TK | 5A | 230VAC | surface-mounted | IP54 | Sentera Controls | STRA1-50L22 2
    New item   -99.76€Transformer fan motor speed controller with automatic restart | TK | 5A | 230VAC | surface-mounted | IP54 | Sentera Controls | STRA1-50L22 3
    New item   -99.76€Transformer fan motor speed controller with automatic restart | TK | 5A | 230VAC | surface-mounted | IP54 | Sentera Controls | STRA1-50L22 4

    Transformer fan motor speed controller with automatic restart | TK | 5A | 230VAC | surface-mounted | IP54 | Sentera Controls | STRA1-50L22

    Code: STRA1-50L22
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  • Product description

    Transformer fan motor speed controller with automatic restart | TK | 5A | 230VAC | surface-mounted | IP54 | Sentera Controls | STRA1-50L22

    STRA1-50L22 – Sentera Controls transformer fan speed controller for single-phase AC motors up to 5 A with TK terminals for motor thermal protection, remote on / off inputs, an alarm output and automatic restart after a power failure. Sinusoidal output voltage: 0-(80)-110-140-170-190-230 VAC.

    Key idea:
    When the fan must operate reliably without supervision: after a power loss and return it restarts by itself, the motor thermal protection is connected directly to the controller, and a fault is reported via the 230 V alarm output. STRA1-50L22 is designed for more powerful fans or several fans together (up to 5 A).
    What it is for STRA1-50L22:
    This model is designed for more powerful fans (up to 5 A) – roof or duct fans in warehouses, workshops, halls or a group of fans.
    Max. motor current
    5 A
    Control
    5-step knob + remote ON/OFF
    Protection functions
    TK, alarm output, auto restart
    Protection
    IP54, surface mounting

    Operating principle

    The 230 VAC supply (L, N, PE), the motor to the regulated output (U/M, N) and the motor thermal protection contacts to the TK terminals are connected. The unregulated L1 output (230 VAC, 2 A) is intended for a damper or auxiliary device, AL – alarm output (230 VAC, 1 A) for fault indication.

    Inside is an autotransformer with several output taps. Each step supplies the motor with a different preset voltage: 0-(80)-110-140-170-190-230 VAC. Control is stepped, not stepless – speed changes in fixed increments. In knob positions 1–5 the output is 110, 140, 170, 190 and 230 VAC; in position 0 the motor and L1 are switched off. The 80 V tap is present but not connected; other voltages can be selected by changing the wiring.

    The controller can be switched on and off remotely: there are normally closed (CC) and normally open (OC) contact inputs for this – for a timer, building automation or an external switch. When power is lost and then returns, the controller restarts automatically.

    The output voltage is sinusoidal because it is obtained by a transformer rather than by electronically “chopping” the sine wave. Therefore the motor runs quietly, heats up less and does not hum – the transformer speed controller is also suitable for AC motors that audibly hum at low speed with an electronic (triac) controller. Engineer's note: the speed of an AC asynchronous motor is reduced by increasing slip, so less energy is saved than with an EC fan or frequency inverter. The greatest advantage of transformer control is quiet and reliable motor operation at all steps.

    Benefits STRA1-50L22?
    TK, alarm, remote on and automatic restart in one enclosure – usually no additional relays or control panel are needed.

    Technical specifications

    Product type Transformer fan speed controller with TK and automatic restart
    Manufacturer / code Sentera Controls / STRA1-50L22
    Series STRA1 (1.5 / 2.5 / 3.5 / 5 / 7.5 / 10 / 13 / 16 / 20 A)
    Supply voltage 230 VAC, 50–60 Hz
    Max. motor current 5 A
    Regulated output (U/M, N) 0-(80)-110-140-170-190-230 VAC, sinusoidal voltage; version L22
    Unregulated output (L1) 230 VAC, 2 A (off in position 0)
    Alarm output (AL) 230 VAC, 1 A – for fault indication
    Motor thermal protection TK terminals
    Remote on / off CC (normally closed) and OC (normally open) contact inputs
    Automatic restart After a power failure
    Control 5-step knob with OFF position
    Indication Green LED – device switched on
    Fuse T-8.0 A-H, 5×20 mm
    Housing Plastic R-ABS, UL94-V0, grey RAL 7035
    Protection class IP54 (EN 60529), for indoor use only
    Operating environment -20…+35 °C, 5–95 % rH non-condensing
    Dimensions A / B / C / D / E 170 / 255 / 140 / 155 / 194 mm (according to the datasheet drawing)
    Weight 5.6 kg net / 5.9 kg gross
    Packaging dimensions 270×180×150 mm
    Compliance LVD 2014/35/EU, EMC 2014/30/EU (EN 61326), RoHS 2011/65/EU, WEEE 2012/19/EU

    Manufacturer documentation

    ✔ Recommended by Elektrotechnikos sprendimai

    Original manufacturer documentation – technical data, wiring diagrams and installation instructions.

    Main functions

    • TK terminals – the motor thermal protection contacts are connected directly to the controller.
    • Automatic restart – when power returns after a failure, the fan restarts without human intervention.
    • Remote ON/OFF (CC / OC) – timer, BMS or external switch with an NC or NO contact.
    • Alarm output AL (230 VAC, 1 A) – for fault indication – a lamp, signal or automation system.
    • Unregulated L1 output (2 A) – for a damper actuator or other device.
    • Sinusoidal output voltage – quiet motor operation at all 5 steps.

    Where is it used?

    • Production, storage and technical premises
    • Commercial buildings with continuously running ventilation
    • Farm and livestock buildings
    • Fans with motor thermal protection (TK)
    • Sites controlled by a timer or building automation

    On-demand operation

    For the electrician.
    TK, alarm and remote control – at the terminals, without additional relays.
    For the ventilation installer.
    Automatic restart after a power failure – fewer call-outs to the site.
    For the building manager.
    Fault signal at the AL output and simple manual speed selection.

    Application guide: how it is used in practice

    Typical STRA1-50L22 applications:

    Site What is connected Result Installer's note
    Fan with TK Motor TK contacts → TK, TK If the motor overheats, the controller stops it and signals a fault The motor must have accessible TK contacts
    Operation by timer / BMS Timer NO contact → OC (or NC → CC) Ventilation is switched on and off remotely The speed is still set by the knob
    Fault signalling Signal lamp or automation → AL A fault is visible immediately AL load – up to 1 A, 230 VAC
    Site without permanent supervision Standard connection After a power failure the fan restarts by itself Check that automatic restart is safe for the process
    Fan with damper Damper actuator → L1, N The damper opens when the fan is switched on L1 load – up to 2 A

    How to select the controller current

    Rated current of the motor(s) Recommended model
    up to 1.5 A STRA1-15L22 (1.5 A)
    1.5–2.5 A STRA1-25L22 (2.5 A)
    2.5–3.5 A STRA1-35L22 (3.5 A)
    3.5–5 A STRA1-50L22 (5 A) ← this model
    5–7.5 A STRA1-75L22 (7.5 A)
    7.5–10 A STRA1100L22 (10 A)
    10–13 A STRA1130L22 (13 A)
    13–16 A STRA1160L20 (16 A)
    16–20 A STRA1200L20 (20 A)
    Rule: controller max. current ≥ motor rated current (see the motor nameplate). When connecting several fans – motors of the same type – add up their rated currents.
    When to choose another solution: no need for TK and remote control – the simpler STR-1; control by a 0-10 VDC signal – STVS1; Modbus RTU – RTVS8; speed switching by an external switch – RTR-1; smoke extraction button – SER-1; stepless electronic control – EVS-1; for an EC fan – SDP potentiometers; for a three-phase motor – STR-4.

    Pros

    • Sinusoidal output voltage – quiet motor operation
    • TK terminals for motor thermal protection
    • Automatic restart after a power failure
    • Remote ON/OFF (NC and NO inputs)
    • Alarm output 230 VAC / 1 A
    • Unregulated L1 output (2 A)
    • IP54 enclosure

    Cons / limitations

    • Step control, not stepless
    • Heavy weight and large dimensions (5.6 kg net)
    • No 0-10 VDC input and no Modbus – the speed is set only with the knob
    • Single-phase AC motors only; not suitable for EC fans
    • Operating temperature up to +35 °C, indoor use only

    Safety and installation notes

    • Installation and connection must be carried out by a qualified electrician with the power disconnected.
    • Always connect the protective earth (PE).
    • The rated current of the motor (or the total of several motors) must not exceed 5 A; replace the fuse only with one of the same type and rating.
    • The controller is intended only for single-phase, voltage-controllable AC motors; it is not suitable for EC fans or three-phase motors.
    • If the motor has TK contacts – connect them; otherwise follow the installation instructions regarding the TK terminals.
    • Before using automatic restart, assess whether an unexpected fan start is safe for people and equipment.
    • For indoor use only (-20…+35 °C).

    Quick selection guide

    5 A
    230 VAC
    TK
    Auto-start
    Alarm
    IP54
    Suitable when you need:
    • quiet stepped AC fan control up to 5 A;
    • motor thermal protection (TK) and a fault signal;
    • remote on and automatic restart after power failure.
    Check before use:
    • the motor rated current and whether it has TK contacts;
    • whether the step voltages 0-(80)-110-140-170-190-230 VAC are suitable;
    • the installation location – weight, dimensions and ambient temperature (up to +35 °C).
    Important reminder: STRA1-50L22 does not control EC fans or three-phase motors.

    FAQ

    What happens during a power failure?
    When voltage returns, the controller restarts automatically – there is no need to switch the fan on again.
    How do I control it from a timer or BMS?
    Via the remote switch-on inputs: OC – for a normally open contact, CC – for a normally closed contact.
    What is the AL output for?
    For fault indication, 230 VAC, up to 1 A.
    Can it be controlled with a 0-10 V signal?
    No, the STVS1 series is intended for that; for Modbus RTU – the RTVS8 series.
    Can several fans be connected?
    Yes, provided their total rated current does not exceed 5 A.

    Transformer fan motor speed controller with automatic restart | TK | 5A | 230VAC | surface-mounted | IP54 | Sentera Controls | STRA1-50L22

    Sentera STRA1-50L22 – transformer fan speed controller up to 5 A, 230 VAC, TK terminals, automatic restart after power failure, remote ON/OFF, alarm output, sinusoidal voltage, IP54.

    Illustrative image may have been created using AI. The appearance of the product may differ slightly from the image shown. Please refer to the technical specification.

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