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  • New item   -315.49€Transformer fan motor speed controller | 20A | 230VAC | surface-mounted | IP54 | Sentera Controls | STR-1200L20

    Transformer fan motor speed controller | 20A | 230VAC | surface-mounted | IP54 | Sentera Controls | STR-1200L20

    Code: STR-1200L20
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  • Product description

    Transformer fan motor speed controller | 20A | 230VAC | surface-mounted | IP54 | Sentera Controls | STR-1200L20

    STR-1200L20 – Sentera Controls transformer fan speed controller for single-phase AC motors up to 20 A. The speed is switched with a 5-position knob, and the motor is supplied with sinusoidal voltage at all steps (0-(80)-100-120-140-170-230 VAC) – quiet operation, without the hum of electronic control.

    Key idea:
    The simplest and most reliable way to control an AC fan: a knob with 5 speeds and an OFF position, a green LED and an unregulated 230 V output. STR-1200L20 is designed for high-power fans or fan groups in industrial and commercial premises (up to 20 A).
    What it is for STR-1200L20:
    This model is intended for high-power fans (up to 20 A) – industrial fans in production halls, warehouses, farm buildings or a larger group of fans.
    Max. motor current
    20 A
    Control
    5-step knob + OFF
    Output steps
    0-(80)-100-120-140-170-230 VAC
    Protection
    IP54, surface mounting

    Operating principle

    The controller is mounted on a wall or structure. The 230 VAC supply (L, N, PE) and the motor to the regulated output (U, N) are connected, and the unregulated L1 output (230 VAC, max. 2 A) can supply a damper actuator or another auxiliary device.

    Inside is an autotransformer with several output taps. Each step supplies the motor with a different preset voltage: 0-(80)-100-120-140-170-230 VAC. Control is stepped, not stepless – speed changes in fixed increments. In knob positions 1–5 the output is 100, 120, 140, 170 and 230 VAC; in position 0 the motor and the L1 output are switched off. The 80 V tap is not used as factory default; other voltages can be selected by changing the wiring.

    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 STR-1200L20?
    The sinusoidal output voltage means quiet motor operation at all steps, and the simple design without electronics means a long and reliable service life.

    Technical specifications

    Product type Transformer fan speed controller
    Manufacturer / code Sentera Controls / STR-1200L20
    Series STR-1 (0.8 / 1 / 1.5 / 2.2 / 3.5 / 5 / 7.5 / 10 / 13 / 16 / 20 A)
    Supply voltage 230 VAC, 50–60 Hz
    Max. motor current 20 A
    Regulated output (U, N) 0-(80)-100-120-140-170-230 VAC, sinusoidal voltage; version L20
    Unregulated output (L1) 230 VAC, max. 2 A (off in position 0)
    Control 5-step knob with OFF position
    Indication Green LED – device switched on
    Fuse T-30.0 A-H, 5×20 mm
    Housing Metal, powder-coated, 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 300 / 430 / 235 / 255 / 355 mm (according to the datasheet drawing)
    Weight 20.60 kg net / 21.15 kg gross
    Packaging dimensions 430×310×255 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

    • 5 speed steps and OFF – the speed is selected with the knob, without any programming.
    • Sinusoidal output voltage – quiet motor operation even at the lowest speed.
    • Unregulated L1 output (2 A) – for a damper actuator or other device that must operate together with the fan.
    • Step voltages can be changed – if required, another tap can be selected by changing the wiring.
    • Green LED – it is clearly visible that the controller is switched on.

    Where is it used?

    • Workshops, production and storage premises
    • Retail, catering and public premises
    • Farm and livestock buildings
    • Duct, roof and axial fans with single-phase AC motors
    • Sites where quiet fan operation is important

    On-demand operation

    For the electrician.
    Simple connection, fuse in the enclosure, PE terminal – no programming.
    For the ventilation installer.
    Sinusoidal voltage – no humming problems, which are common with electronic controllers.
    For the user.
    Clear 5-position knob: OFF and five speeds.

    Application guide: how it is used in practice

    Typical STR-1200L20 applications:

    Site What is connected Result Installer's note
    Production or storage room Fan → U, N Speed is selected with the knob as needed Motor rated current ≤ 20 A
    Fan with damper Damper actuator → L1, N The damper opens when any step is selected L1 load – up to 2 A
    A group of several fans In parallel → U, N All fans run at the same speed Add up the rated currents; motors of the same type
    A motor that hums with an electronic controller Replace with STR-1200L20 Quiet operation at all steps Step control – select the closest speed

    How to select the controller current

    Rated current of the motor(s) Recommended model
    up to 0.8 A STR-1-08L22 (0.8 A)
    0.8–1 A STR-1-10L10 (1 A)
    1–1.5 A STR-1-15L22 (1.5 A)
    1.5–2.2 A STR-1-22L22 (2.2 A)
    2.2–3.5 A STR-1-35L22 (3.5 A)
    3.5–5 A STR-1-50L22 (5 A)
    5–7.5 A STR-1-75L22 (7.5 A)
    7.5–10 A STR-1100L22 (10 A)
    10–13 A STR-1130L22 (13 A)
    13–16 A STR-1160L20 (16 A)
    16–20 A STR-1200L20 (20 A) ← this model
    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: need TK protection, remote on and automatic restart – STRA1 series; 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
    • 5 speed steps and OFF position
    • Unregulated L1 output (2 A)
    • Simple, reliable design without programming
    • IP54 enclosure
    • Wide series range: 0.8–20 A

    Cons / limitations

    • Step control, not stepless
    • Higher weight and larger dimensions than electronic controllers (20.60 kg)
    • No TK protection, 0-10 VDC input or Modbus
    • 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 20 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.
    • For indoor use only (-20…+35 °C).
    • The terminal layout depends on the model group – wire according to the diagram of the specific model.

    Quick selection guide

    20 A
    230 VAC
    5 steps
    Sinusoidal voltage
    IP54
    Suitable when you need:
    • quiet stepped single-phase AC fan control up to 20 A;
    • simple manual control without automation;
    • IP54 enclosure in technical rooms.
    Check before use:
    • the motor rated current and whether it is suitable for voltage control;
    • whether the step voltages 0-(80)-100-120-140-170-230 VAC are suitable;
    • the installation location – weight and dimensions, ambient temperature (up to +35 °C).
    Important reminder: STR-1200L20 does not control EC fans or three-phase motors.

    FAQ

    Why is a transformer speed controller quieter than an electronic one?
    Its output voltage is sinusoidal, so the motor does not hum even at the lowest speed.
    Can it be controlled steplessly?
    No, the speed is changed in 5 steps: 100, 120, 140, 170 and 230 VAC.
    Can several fans be connected?
    Yes, provided their total rated current does not exceed 20 A.
    What is the L1 output for?
    For a damper actuator or other device that must be powered when the fan is on (230 VAC, up to 2 A).
    Does it have motor thermal (TK) protection?
    No. TK terminals, remote switch-on and automatic restart are available in the STRA1 series.

    Transformer fan motor speed controller | 20A | 230VAC | surface-mounted | IP54 | Sentera Controls | STR-1200L20

    Sentera STR-1200L20 – transformer fan speed controller up to 20 A, 230 VAC, 5 steps (0-(80)-100-120-140-170-230 VAC), sinusoidal output voltage, unregulated L1 output, 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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