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  • New item   -301.53€Transformer three-phase fan motor speed controller with timer | TK | 1.5A | 400VAC | surface-mounted | IP54 | Sentera Controls | ST2R4-15L55
    New item   -301.53€Transformer three-phase fan motor speed controller with timer | TK | 1.5A | 400VAC | surface-mounted | IP54 | Sentera Controls | ST2R4-15L55 1
    New item   -301.53€Transformer three-phase fan motor speed controller with timer | TK | 1.5A | 400VAC | surface-mounted | IP54 | Sentera Controls | ST2R4-15L55 2
    New item   -301.53€Transformer three-phase fan motor speed controller with timer | TK | 1.5A | 400VAC | surface-mounted | IP54 | Sentera Controls | ST2R4-15L55 3
    New item   -301.53€Transformer three-phase fan motor speed controller with timer | TK | 1.5A | 400VAC | surface-mounted | IP54 | Sentera Controls | ST2R4-15L55 4
    New item   -301.53€Transformer three-phase fan motor speed controller with timer | TK | 1.5A | 400VAC | surface-mounted | IP54 | Sentera Controls | ST2R4-15L55 5

    Transformer three-phase fan motor speed controller with timer | TK | 1.5A | 400VAC | surface-mounted | IP54 | Sentera Controls | ST2R4-15L55

    Code: ST2R4-15L55
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  • Product description

    Transformer three-phase fan motor speed controller with timer | TK | 1.5A | 400VAC | surface-mounted | IP54 | Sentera Controls | ST2R4-15L55

    ST2R4-15L55 – Sentera Controls two-speed transformer speed controller for three-phase 400 VAC fan motors up to 1.5 A with a built-in programmable timer (day / night, weekly program), LCD display, TK terminals and alarm output.

    Key idea:
    Stand-alone ventilation control without an external clock or controller: high and low speed are selected from 8 voltages, and the built-in weekly timer decides when each one runs.
    What it is for ST2R4-15L55:
    This model is designed for low-power fans (up to 1.5 A) – one or two duct or axial fans in an office, bathroom, kitchen or small room.
    Max. motor current
    1.5 A
    Control
    LCD, keypad, weekly timer
    Signals
    TK, alarm 230 VAC, CC/OC
    Supply / protection
    3×400 VAC + N; IP54

    Operating principle

    The controller is wall-mounted. The 3×400 VAC supply is connected to R, S, T and N, the motor – to U, V, W, the thermal contacts – to TK, the alarm indication – to AL and N, and a thermostat or frost protection contact – to CC (normally closed) or OC (normally open).

    The controller is based on an autotransformer. High and low speed are each assigned one of the voltages: 0, 130, 170, 210, 250, 290, 330 or 400 VAC. Control is in steps, not stepless.

    The output voltage is SINUSOIDAL – without phase cutting as in electronic controllers. Therefore the motor runs quietly even at low speed, does not heat up due to higher harmonics and does not interfere with other equipment. This is the solution for motors that hum or buzz when controlled by an electronic controller.

    Speeds are switched manually via the keypad or automatically according to a programmable day / week timer. The menu is multilingual, and parameters can be read and changed from a computer via USB with the free 3SMUsb software (3SM Center). Engineer's note: reducing the voltage of an AC asynchronous motor increases slip, so less energy is saved than with an EC fan or frequency inverter. The strength of a transformer speed controller is reliability, quietness and simplicity, not maximum efficiency.

    Benefits ST2R4-15L55?
    The entire ventilation regime – speeds, weekly schedule, motor protection and alarm – in one IP54 device, without a separate clock or controller.

    Technical specifications

    Product type Two-speed three-phase fan transformer speed controller with timer
    Manufacturer / code Sentera Controls / ST2R4-15L55
    Series ST2R4 (1.5 / 2.5 / 4 / 6 / 8 / 11 A)
    Supply voltage 3×400 VAC, 50–60 Hz, with neutral (R, S, T, N)
    Max. motor current 1.5 A
    Regulated output (U, V, W) 2 speeds, selected from 0 / 130 / 170 / 210 / 250 / 290 / 330 / 400 VAC; sinusoidal voltage
    Timer Programmable, day / night and weekly functions
    Control LCD display and keypad, multilingual menu
    Connection to a computer USB, 3SMUsb software (3SM Center)
    Unregulated output (L1, N) 230 VAC, 2 A
    Alarm output (AL, N) 230 VAC (motor overheating)
    Motor protection TK terminals for motor thermal contacts
    Start / stop inputs CC (normally closed) and OC (normally open) – for a thermostat, frost protection, etc.
    Housing Sheet steel, polyester powder coating RAL 7035
    Protection class IP54 (EN 60529), for indoor use only
    Operating environment -20…+35 °C, 5–95 % rH non-condensing
    Dimensions A 300 / B 325 / C 150 / D 255 / E 255 mm (letter meanings – according to the datasheet drawing)
    Packaging (L × W × H) 340×310×210 mm
    Weight 11.36 kg (net)
    Compliance LVD 2014/35/EU (EN 60335-1, EN 61558-1), EMC 2014/30/EU (EN 61000-6-2, EN 61000-6-3, EN 60730-1), RoHS 2011/65/EU

    Manufacturer documentation

    ✔ Recommended by Elektrotechnikos sprendimai

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

    Main functions

    • Built-in timer – day / night and weekly program – ventilation runs on a schedule.
    • 2 speeds from 8 voltages – high and low speed are selected within 0–400 VAC.
    • LCD and keypad – clear multilingual menu, manual speed switching.
    • USB ir 3SMUsb – reading, changing and writing parameters with a computer.
    • TK and alarm 230 VAC – motor overheating protection and fault signal.
    • CC / OC inputs – thermostat, frost protection or other automation.

    Where is it used?

    • Industrial HVAC systems with three-phase fans
    • Ventilation of offices, retail and public buildings according to the working schedule
    • Production halls with shifts
    • Warehouses and agricultural buildings

    On-demand operation

    For the electrician.
    TK, alarm and external contact circuits are connected directly to the controller.
    For the ventilation installer.
    Speeds and schedule are set via the menu or from a computer via USB.
    For the building owner.
    Ventilation is automatically reduced outside working hours – less noise and lower costs.

    Application guide: how it is used in practice

    Typical ST2R4-15L55 applications:

    Site What is connected Result Installer's note
    Office, shop Weekly program in the timer High speed during working hours, low at night and at weekends Set the exact time and weekly schedule
    Production hall with shifts Timer + keypad Schedule according to shifts, speed switched manually when needed Select the speeds from 8 voltages according to the air demand
    Supply air system in winter Frost protection contact → CC If there is a risk of freezing, the fan is stopped Use a voltage-free contact
    Control room, BMS AL, N → signal lamp or BMS input Motor overheating is signalled immediately Connect the motor TK to the TK terminals
    Several sites with identical settings Computer → USB (3SMUsb) Parameters are quickly copied to other controllers Free software (3SM Center)

    How to select the controller current

    Rated current of the motor(s) Recommended model
    up to 1.5 A ST2R4-15L55 (1.5 A) ← this model
    1.5–2.5 A ST2R4-25L55 (2.5 A)
    2.5–4 A ST2R4-40L55 (4 A)
    4–6 A ST2R4-60L55 (6 A)
    6–8 A ST2R4-80L55 (8 A)
    8–11 A ST2R4110L55 (11 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. Choose a margin if the motor current is close to the model's limit or the fan often runs at the maximum step.
    When to choose another solution: with an external clock and two knobs – SC2A4; single-speed with NO/NC and alarm – STRA4 or STTA4; for 0-10 VDC control – STVS4; for the simplest control – STR-4.

    Pros

    • Built-in daily / weekly timer
    • LCD display, multilingual menu
    • USB and the free 3SMUsb software
    • TK, alarm 230 VAC, CC / OC inputs
    • Sinusoidal output voltage
    • IP54 enclosure

    Cons / limitations

    • Only 2 speeds during operation (selected from 8 voltages)
    • No Modbus and no analogue 0-10 VDC input
    • Step (not stepless) control – the speed is selected from fixed voltages
    • Heavy weight and large dimensions compared with electronic controllers
    • Indoor use only, operating temperature up to +35 °C
    • Not suitable for EC fans and motors controlled by a frequency inverter

    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).
    • Check that the motor is suitable for voltage control and that its rated current does not exceed 1.5 A.
    • The supply requires a neutral (N).
    • Connect only dry contacts to the CC / OC inputs.
    • The device is heavy – fix it to a load-bearing wall or structure using suitable fixings.
    • For indoor use only (-20…+35 °C, non-condensing); leave space for cooling.

    Quick selection guide

    1.5 A
    3×400 VAC
    Timer
    LCD
    TK
    IP54
    Suitable when you need:
    • a three-phase fan up to 1.5 A with a weekly schedule without an external controller;
    • sites with working / non-working hours mode;
    • motors with thermal contacts and a fault signal.
    Check before use:
    • the motor rated current and whether it is voltage-controllable;
    • whether two speeds are sufficient;
    • the installation location (11.36 kg, up to +35 °C).
    Important reminder: ST2R4-15L55 controls voltage-controllable AC motors; it is not suitable for EC fans.

    FAQ

    Is an external clock required?
    No, a timer with day / night and weekly functions is built in.
    What voltages can be assigned to the speeds?
    0, 130, 170, 210, 250, 290, 330 and 400 VAC.
    Can it be configured from a computer?
    Yes, via USB with the free 3SMUsb software (3SM Center).
    How does it differ from SC2A4?
    SC2A4 sets the speeds with knobs and switches them with an external clock; ST2R4 has a built-in timer, LCD and USB.
    Is there motor protection?
    Yes, TK terminals and a 230 VAC alarm output.

    Transformer three-phase fan motor speed controller with timer | TK | 1.5A | 400VAC | surface-mounted | IP54 | Sentera Controls | ST2R4-15L55

    Sentera ST2R4-15L55 – transformer speed controller for three-phase fans with timer up to 1.5 A, 3×400 VAC, 2 speeds, weekly program, LCD, USB, TK, alarm, 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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