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  • New item   -153.57€Transformer fan motor speed controller with timer | TK | 2.5A | 230VAC | surface-mounted | IP54 | Sentera Controls | ST2R1-25L25

    Transformer fan motor speed controller with timer | TK | 2.5A | 230VAC | surface-mounted | IP54 | Sentera Controls | ST2R1-25L25

    Code: ST2R1-25L25
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  • Product description

    Transformer fan motor speed controller with timer | TK | 2.5A | 230VAC | surface-mounted | IP54 | Sentera Controls | ST2R1-25L25

    ST2R1-25L25 – Sentera Controls transformer fan speed controller with a built-in programmable timer and LCD display, for single-phase 230 VAC voltage-controllable motors up to 2.5 A. Two speeds are selected from 80–230 VAC steps; it has TK terminals for motor protection, a fault output and remote switch-on inputs.

    Key idea:
    Stand-alone ventilation controller: the clock is built in, so no external timer is needed. A day / night or day-of-week schedule is configured via the keypad, and the motor runs quietly thanks to the sinusoidal output voltage.
    What it is for ST2R1-25L25:
    This model is intended for medium-power fans (up to 2.5 A) – duct fans in offices, classrooms, retail premises or 2–3 smaller fans together.
    Max. motor current
    2.5 A
    Timer
    Day / night, weekly program
    Speeds
    2, from 80–230 VAC steps
    Protection
    IP54, TK, fault output

    Operating principle

    The controller is wall-mounted in the room. Connected are the 230 VAC supply (L, N, PE), the motor (U, N), the motor thermal contacts (TK) and, as needed, a remote switch-on contact (CC or OC), the fault signal (AL) and the unregulated output L1 for a damper actuator.

    The heart of the controller is an autotransformer with several taps (steps). Each step supplies the motor with a different fixed voltage, while the output voltage remains SINUSOIDAL, as in the mains. As a result, the motor runs quietly even at low speed – the transformer speed controller is also suitable for motors that hum or heat up with an electronic (semiconductor) controller.

    High and low speed are each assigned one voltage from the steps 80, 100, 120, 150, 170, 190 and 230 VAC. The speed is switched manually via the keypad or automatically according to the built-in clock program (day / night and day / week functions). Settings are shown on an LCD display with a multilingual menu, and via the USB connection they can be read, changed and saved with the free 3SMUsb software.

    Control is in steps, not stepless: the speed changes in jumps between fixed voltages. Engineer's note: the speed at each step depends on the motor and fan characteristics, so after commissioning it is worth checking that the motor reliably starts at the lowest step used. The TK terminals are intended for motor thermal protection, and the fault output AL (230 VAC / 1 A) sends a signal to an alarm system or BMS.

    Benefits ST2R1-25L25?
    Timer, two speeds, TK protection, fault signal and USB configuration in one IP54 enclosure – scheduled ventilation without any additional devices.

    Technical specifications

    Product type Transformer fan speed controller with timer
    Manufacturer / code Sentera Controls / ST2R1-25L25
    Series ST2R1 (1.5 / 2.5 / 3.5 / 5 / 7.5 / 10 / 13 A)
    Supply voltage 230 VAC, 50–60 Hz
    Max. motor current 2.5 A
    Speeds 2 (high and low)
    Selectable voltages 80 / 100 / 120 / 150 / 170 / 190 / 230 VAC
    Output voltage waveform Sinusoidal (autotransformer)
    Timer Programmable clock, day / night and day / week functions
    Control Keypad, LCD display with multilingual menu
    PC configuration USB connection, 3SMUsb software (free)
    Motor thermal protection TK terminals
    Remote on / off CC (NC contact), OC (NO contact)
    Fault output AL, 230 VAC / 1 A
    Unregulated output L1 230 VAC, 1 A
    Fuse 5×20 mm, T-4.0 A-H
    Housing plastic, 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
    Mounting dimensions A 170 × B 250 × C 136 mm (mounting D 155 / E 193 mm)
    Packaging dimensions 216×130×110 mm
    Weight 3.79 kg net / 4.01 kg gross
    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

    • Built-in programmable clock – day / night and weekly schedule without an external timer.
    • Two speeds from 7 voltages – an 80–230 VAC step is selected for each speed.
    • LCD and keypad – multilingual menu, manual speed selection.
    • USB ir 3SMUsb – reading, changing and saving parameters with a computer.
    • TK protection and fault output – connection of motor thermal contacts, AL output (230 VAC / 1 A) for the fault signal.
    • Remote switch-on – via a CC (NC) or OC (NO) contact.

    Where is it used?

    • Offices, schools, kindergartens – ventilation according to the working schedule
    • Retail and service premises with a weekly schedule
    • Sports halls, community premises
    • Production and warehouse premises
    • Duct and roof fans with single-phase AC motors

    On-demand operation

    For the electrician.
    All the required terminals: TK, CC/OC, AL, L1 and PE – no additional relays needed.
    For the ventilation installer.
    Speeds and schedule are set on site via the keypad or from a computer via USB.
    For the building owner.
    Ventilation runs on a schedule – lower speed and lower costs outside working hours.

    Application guide: how it is used in practice

    Typical ST2R1-25L25 applications:

    Site What is connected Result Installer's note
    Office with a working schedule Fan → U, N; program in the timer High speed on working days, low speed at night and at weekends The schedule is conveniently prepared via USB with 3SMUsb
    Motor with thermal contacts Motor TK → TK; signalling → AL The motor is protected, and the fault signal is passed on AL – 230 VAC / 1 A
    Control from a BMS or fire alarm system NC contact → CC or NO contact → OC The fan is stopped / started remotely Choose the input according to the contact type
    Fan with damper Damper actuator → L1, N The damper is powered together with the fan L1 load – up to 1 A

    How to select the controller current

    Rated current of the motor(s) Recommended model
    up to 1.5 A ST2R1-15L25 (1.5 A)
    1.5–2.5 A ST2R1-25L25 (2.5 A) ← this model
    2.5–3.5 A ST2R1-35L25 (3.5 A)
    3.5–5 A ST2R1-50L25 (5 A)
    5–7.5 A ST2R1-75L25 (7.5 A)
    7.5–10 A ST2R1100L25 (10 A)
    10–13 A ST2R1130L25 (13 A)
    Rule: controller max. current ≥ rated current of the motor (or the sum of several motors) from the motor nameplate. For a transformer controller the motor starting current is already taken into account by the manufacturer, so no additional margin is needed. Connect several fans only with AC motors of the same type that are voltage-controllable.
    When to choose another solution: the timer will be external – SC2A1 (with TK) or SC2-1 series; stepless control by a 0-10 VDC signal or Modbus – electronic EVS-1 series; temperature-based speed – GTT-1 series.

    Pros

    • Built-in programmable clock (day / night, week)
    • Sinusoidal output voltage – quiet motor operation
    • LCD display, multilingual menu
    • USB configuration with 3SMUsb
    • TK protection and fault output
    • Remote switch-on via NC / NO contact
    • IP54 enclosure

    Cons / limitations

    • Step, not stepless control (7 voltages)
    • Heavy weight (3.79 kg) and large dimensions
    • No 0-10 VDC input and no Modbus
    • Single-phase voltage-controllable AC motors only; not suitable for EC fans
    • Indoor use only, up to +35 °C
    • Load of the unregulated L1 output is limited (1 A)

    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 total rated current of the connected motors must not exceed 2.5 A.
    • Replace the fuse only with one of the same type and rated current as specified in the datasheet.
    • The controller is intended for indoor use only (-20…+35 °C).
    • Only potential-free contacts are connected to CC / OC; the TK terminals – only to the motor thermal contacts.
    • Terminal layout differs depending on the model – wire according to the diagram of the specific model.

    Quick selection guide

    2.5 A
    230 VAC
    Timer + LCD
    TK
    IP54
    Suitable when you need:
    • schedule-based control of a fan up to 2.5 A;
    • quiet sinusoidal voltage control;
    • motor TK protection and a fault signal.
    Check before use:
    • the motor rated current and whether it is voltage-controllable;
    • which voltages (80–230 VAC) are needed for high and low speed;
    • the operating schedule (day / night, days of the week);
    • the ambient temperature (up to +35 °C).
    Important reminder: ST2R1-25L25 does not control EC fans or three-phase motors; it has no Modbus connection.

    FAQ

    Is an external timer required?
    No, the clock is built in: day / night and day / week programs are set via the keypad or via USB.
    What voltages can be selected for the speeds?
    80, 100, 120, 150, 170, 190 or 230 VAC – one each for high and low speed.
    Can the speed be switched manually?
    Yes, either of the two speeds can be selected and activated via the keypad.
    How do I connect the motor thermal protection?
    The motor TK contacts are connected to the TK terminals, and the fault signal is transmitted via the AL output (230 VAC / 1 A).
    Can it be connected to a BMS via Modbus?
    No, there is no Modbus. It is connected to a BMS via the CC / OC inputs and the AL output.

    Transformer fan motor speed controller with timer | TK | 2.5A | 230VAC | surface-mounted | IP54 | Sentera Controls | ST2R1-25L25

    Sentera ST2R1-25L25 – transformer fan speed controller with programmable timer and LCD, up to 2.5 A, 230 VAC, 2 speeds from 80–230 VAC steps, TK protection, fault output, USB, 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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