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  • New item   -316.23€Transformer three-phase fan motor speed controller with thermal protection | 4A | 400VAC | surface-mounted | IP54 | Sentera Controls | STTA4-40L40
    New item   -316.23€Transformer three-phase fan motor speed controller with thermal protection | 4A | 400VAC | surface-mounted | IP54 | Sentera Controls | STTA4-40L40 1
    New item   -316.23€Transformer three-phase fan motor speed controller with thermal protection | 4A | 400VAC | surface-mounted | IP54 | Sentera Controls | STTA4-40L40 2
    New item   -316.23€Transformer three-phase fan motor speed controller with thermal protection | 4A | 400VAC | surface-mounted | IP54 | Sentera Controls | STTA4-40L40 3
    New item   -316.23€Transformer three-phase fan motor speed controller with thermal protection | 4A | 400VAC | surface-mounted | IP54 | Sentera Controls | STTA4-40L40 4

    Transformer three-phase fan motor speed controller with thermal protection | 4A | 400VAC | surface-mounted | IP54 | Sentera Controls | STTA4-40L40

    Code: STTA4-40L40
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  • Product description

    Transformer three-phase fan motor speed controller with thermal protection | 4A | 400VAC | surface-mounted | IP54 | Sentera Controls | STTA4-40L40

    STTA4-40L40 – Sentera Controls transformer speed controller for three-phase 400 VAC fan motors up to 4 A with motor thermal protection (setting range 4–6.3 A), TK terminals, alarm output and external on/off contacts.

    Key idea:
    A controller for when motor protection is the priority: the thermal protection current is set according to the motor, the motor thermal contacts are connected, and a fault is signalled via the 230 VAC alarm output. After a power failure the controller restarts automatically.
    What it is for STTA4-40L40:
    This model is designed for more powerful fans (up to 4 A) – roof or duct fans in warehouses, workshops, halls or a group of fans.
    Max. motor current
    4 A
    Thermal protection
    4–6.3 A (setting range)
    Signals
    TK, alarm 230 VAC / 1 A, NO/NC
    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 motor thermal contacts – to TK, the alarm – to AL, and an external on / off contact – to the NC or NO terminals.

    The controller is based on an autotransformer with several taps (steps). When the knob is turned, the motor is switched to another tap, so the output voltage changes in steps rather than steplessly. Regulated output voltages of the L40 version: 0 – 130 – 180 – 230 – 300 – 400 VAC; of the L50 version (14 A model) – 0 – 170 – 220 – 260 – 300 – 400 VAC (the 130 VAC tap is present but not connected). Position 0 – motor off.

    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.

    The thermal protection is set within the range 4–6.3 A according to the motor rated current. Together with the motor thermal contacts (TK), this provides double motor protection; a fault is signalled via the 230 VAC / 1 A alarm output. After a power failure, the controller restarts automatically. Engineer's note: reducing the voltage of an AC induction motor increases slip, so energy savings are lower than with an EC fan or a frequency inverter. The strength of a transformer controller is reliability, quietness and simplicity, not maximum efficiency.

    Benefits STTA4-40L40?
    Quiet step speed control, adjustable motor thermal protection, TK, alarm and remote switch-on in one IP54 enclosure – fewer components in the control panel and a simpler diagram.

    Technical specifications

    Product type Transformer three-phase fan motor speed controller with thermal protection
    Manufacturer / code Sentera Controls / STTA4-40L40
    Series STTA4 (1.5 / 2.5 / 4 / 6 / 8 / 11 / 14 A)
    Supply voltage 3×400 VAC, 50–60 Hz, with neutral (R, S, T, N)
    Max. motor current 4 A
    Regulated output (U, V, W) 0 – 130 – 180 – 230 – 300 – 400 VAC (positions 0–5), sinusoidal voltage
    Thermal protection setting range 4–6.3 A
    Unregulated output (L1) 230 VAC, 50–60 Hz; the technical data state 1 A, the terminal description – 2 A (calculate with 1 A)
    Alarm output (AL) 230 VAC, 1 A
    Motor protection TK terminals for motor thermal contacts
    External on / off NC and NO contact inputs
    Restart after a power failure Automatic
    Control 5-position rotary switch with OFF position
    Indication Blue LED – device switched on
    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 300 / B 425 / C 185 / D 255 / E 355 mm (letter meanings – according to the datasheet drawing)
    Packaging (L × W × H) 440×310×200 mm
    Weight 18.5 kg (net)
    Compliance LVD 2014/35/EU, EMC 2014/30/EU (EN 61326), WEEE 2012/19/EU, RoHS 2011/65/EU

    Manufacturer documentation

    ✔ Recommended by Elektrotechnikos sprendimai

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

    Main functions

    • Adjustable thermal protection – setting range 4–6.3 A – the protection is adapted to the specific motor.
    • TK terminals – connection of motor thermal contacts.
    • Alarm output 230 VAC / 1 A – a fault signal for a lamp, siren or BMS.
    • NO / NC inputs – switching on and off by a thermostat, timer or automation system.
    • Automatic restart – after a power failure ventilation resumes by itself.
    • Sinusoidal output voltage – quiet motor operation at all 5 steps.

    Where is it used?

    • Industrial ventilation systems with three-phase fans
    • Sites where motor protection and a fault signal are required
    • Production, storage and agricultural buildings
    • Continuously running extract fans

    On-demand operation

    For the electrician.
    Motor protection, TK and alarm are already integrated – fewer separate devices in the control panel.
    For the automation integrator.
    NO / NC inputs and a 230 VAC alarm are easily linked to a BMS or thermostat.
    For the building owner.
    The motor is protected against overheating and overload, and faults are reported immediately.

    Application guide: how it is used in practice

    Typical STTA4-40L40 applications:

    Site What is connected Result Installer's note
    Extract fan in a production hall Motor → U, V, W; TK → TK terminals The motor is protected both against overheating and against exceeding the set current Set the thermal protection according to the motor rated current (4–6.3 A)
    Control room, BMS AL → signal lamp or BMS input A fault is visible at once Alarm output load – up to 1 A
    Temperature-based ventilation Thermostat contact → NO input The fan switches on when the temperature rises Select the speed with the knob
    Rarely visited site Standard supply R, S, T, N After a power failure the fan restarts by itself Convenient for remote sites

    How to select the controller current

    Rated current of the motor(s) Recommended model
    up to 1.5 A STTA4-15L40 (1.5 A)
    1.5–2.5 A STTA4-25L40 (2.5 A)
    2.5–4 A STTA4-40L40 (4 A) ← this model
    4–6 A STTA4-60L40 (6 A)
    6–8 A STTA4-80L40 (8 A)
    8–11 A STTA4110L40 (11 A)
    11–14 A STTA4140L50 (14 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. Select the thermal protection setting according to the motor rated current.
    When to choose another solution: without adjustable thermal protection – STRA4 (TK, NO/NC, alarm) or STRS4 (TK); for control by a 0-10 VDC signal – STVS4; for two speeds – SC2A4 or ST2R4; for the simplest control – STR-4.

    Pros

    • Adjustable motor thermal protection
    • TK terminals
    • Alarm output 230 VAC / 1 A
    • NO / NC external control inputs
    • Automatic restart after a power failure
    • Sinusoidal output voltage

    Cons / limitations

    • The current of the unregulated L1 output is stated inconsistently in the datasheet (1 A / 2 A) – calculate with 1 A
    • Speed is changed only with the knob – there is no analogue 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 4 A.
    • The supply requires a neutral (N).
    • Set the thermal protection according to the motor rated current, not higher.
    • Connect only dry contacts to the NO / NC 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

    4 A
    3×400 VAC
    Thermal protection 4–6.3 A
    TK
    Alarm
    IP54
    Suitable when you need:
    • a three-phase fan up to 4 A with adjustable thermal protection;
    • sites where a fault signal and remote on are required;
    • automatic recovery after power failure.
    Check before use:
    • the motor rated current – whether it falls within the thermal protection range 4–6.3 A;
    • whether the motor has thermal contacts (TK);
    • the installation location (18.5 kg, up to +35 °C).
    Important reminder: STTA4-40L40 does not control EC fans; speed is changed in steps via the knob.

    FAQ

    What current is the thermal protection set to?
    In this model – within the range 4–6.3 A, according to the motor rated current.
    Will it restart after a power failure?
    Yes, the datasheet specifies automatic start.
    What is the alarm output for?
    For the fault signal: 230 VAC, up to 1 A – for a lamp, siren or BMS.
    How does it differ from STRA4?
    STTA4 has adjustable thermal protection with a setting range and automatic restart after power failure.
    What voltages does the motor receive?
    0, 130, 180, 230, 300 and 400 VAC.

    Transformer three-phase fan motor speed controller with thermal protection | 4A | 400VAC | surface-mounted | IP54 | Sentera Controls | STTA4-40L40

    Sentera STTA4-40L40 – transformer speed controller for three-phase fans up to 4 A with thermal protection (4–6.3 A), TK, alarm output, NO/NC inputs, 3×400 VAC, 5 steps, 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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