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  • New item   -144.49€Transformer fan motor speed controller with airflow-dependent gas valve interlock | TK | 5A | 230VAC | surface-mounted | IP54 | Sentera Controls | SFPR1-50L22
    New item   -144.49€Transformer fan motor speed controller with airflow-dependent gas valve interlock | TK | 5A | 230VAC | surface-mounted | IP54 | Sentera Controls | SFPR1-50L22 1
    New item   -144.49€Transformer fan motor speed controller with airflow-dependent gas valve interlock | TK | 5A | 230VAC | surface-mounted | IP54 | Sentera Controls | SFPR1-50L22 2
    New item   -144.49€Transformer fan motor speed controller with airflow-dependent gas valve interlock | TK | 5A | 230VAC | surface-mounted | IP54 | Sentera Controls | SFPR1-50L22 3
    New item   -144.49€Transformer fan motor speed controller with airflow-dependent gas valve interlock | TK | 5A | 230VAC | surface-mounted | IP54 | Sentera Controls | SFPR1-50L22 4

    Transformer fan motor speed controller with airflow-dependent gas valve interlock | TK | 5A | 230VAC | surface-mounted | IP54 | Sentera Controls | SFPR1-50L22

    Code: SFPR1-50L22
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  • Product description

    Transformer fan motor speed controller with airflow-dependent gas valve interlock | TK | 5A | 230VAC | surface-mounted | IP54 | Sentera Controls | SFPR1-50L22

    SFPR1-50L22 – Sentera Controls transformer fan speed controller with flow monitoring for single-phase 230 VAC voltage-controllable motors up to 5 A. The speed is set with a 5-step selector switch, and the contact of a flow sensor or pressure switch controls the relay output for a gas valve or actuator. It has TK terminals for motor thermal protection.

    Key idea:
    The controller not only changes the fan speed but also confirms that there actually is flow: the relay output (e.g. for a gas valve) is switched on only when the flow or pressure sensor contact closes within 60 s of start-up. This is a simple “no flow – no enable” interlock.
    What it is for SFPR1-50L22:
    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
    Airflow monitoring
    FL input + relay COM/NO/NC
    Control
    5 steps, 110–230 VAC
    Protection
    IP54, TK terminals

    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), the flow sensor or pressure switch contact (FL), the remote switch-on or thermostat contact (NC input) and the relay output COM / NO / NC.

    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.

    The manual 5-position selector switch selects the output voltage 110 – 140 – 170 – 190 – 230 VAC; in position 0 the controller is off (the 80 VAC tap is present but not connected at the factory – other voltages can be selected by changing the internal wiring). The unregulated output L1 (230 VAC / 2 A) is active in all operating positions.

    After the fan is started, the controller waits for flow confirmation: if the FL contact closes within 60 s, the relay (230 VAC / 2 A) is switched on to control a gas valve or actuator. The TK terminals protect the motor against overheating. 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.

    Benefits SFPR1-50L22?
    Fan speed control and airflow confirmation interlock in one IP54 enclosure – no separate controller or time relay needed.

    Technical specifications

    Product type Transformer fan speed controller with airflow monitoring
    Manufacturer / code Sentera Controls / SFPR1-50L22
    Series SFPR1 (3.5 / 5 / 7.5 / 10 / 12 A)
    Supply voltage 230 VAC ±10 %, 50–60 Hz
    Max. motor current 5 A
    Output voltage steps 0 – 110 – 140 – 170 – 190 – 230 VAC ±5 % (80 VAC tap not connected)
    Output voltage waveform Sinusoidal (autotransformer)
    Control 5-position selector switch + OFF position
    Airflow monitoring FL input for a flow sensor or pressure switch; confirmation within 60 s of start-up
    Relay output COM / NO / NC, 230 VAC / 2 A (for a gas valve or actuator)
    Motor thermal protection TK terminals
    Remote switch-on / thermostat NC input
    Unregulated output L1 230 VAC / 2 A
    Indication Green LED – device switched on
    Fuse 5×20 mm, T-8.0 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
    Cable diameter 8–13 mm
    Dimensions A 200 × B 305 × C 155 mm (mounting D 183 / E 236 mm)
    Weight 5.60 kg net / 6.35 kg gross
    Compliance LVD 2014/35/EU, EN 61000-6-1, EN 61558-2-13, 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

    • Airflow confirmation – the relay switches on only when the flow or pressure sensor contact closes within 60 s of start-up.
    • Relay output COM / NO / NC – for a gas valve or actuator, 230 VAC / 2 A.
    • 5-step manual control – 110–230 VAC, with OFF position.
    • TK protection – connection of motor thermal contacts.
    • Remote switch-on or thermostat – via the NC input.
    • Unregulated output L1 – 230 VAC / 2 A for a damper or other device.

    Where is it used?

    • Systems in which a gas valve or actuator may only be switched on when fan airflow is present
    • Extract ventilation with flow or pressure monitoring
    • Industrial and technical premises
    • Fans with single-phase AC motors and TK contacts

    On-demand operation

    For the electrician.
    All interlock elements in one enclosure: FL input, COM/NO/NC relay, TK and PE.
    For the heating and ventilation installer.
    Simple “flow → enable” logic without a separate controller.
    For the building owner.
    The valve or actuator does not switch on until the fan generates airflow.

    Application guide: how it is used in practice

    Typical SFPR1-50L22 applications:

    Site What is connected Result Installer's note
    Fan with gas valve interlock Pressure switch → FL; gas valve → COM / NO The valve opens only after airflow is confirmed Airflow must be confirmed within 60 s
    Motor with thermal contacts Motor TK → TK The motor is protected against overheating Connect according to the manufacturer's diagram
    Thermostat control Thermostat NC contact → NC input The fan is started / stopped according to temperature Connect a potential-free contact
    Fan with damper Damper actuator → L1, N The damper is powered together with the fan L1 load – up to 2 A

    How to select the controller current

    Rated current of the motor(s) Recommended model
    up to 3.5 A SFPR1-35L22 (3.5 A)
    3.5–5 A SFPR1-50L22 (5 A) ← this model
    5–7.5 A SFPR1-75L22 (7.5 A)
    7.5–10 A SFPR1100L22 (10 A)
    10–12 A SFPR1130L22 (12 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: airflow monitoring not needed – SC2A1 (two speeds, TK) or ST2R1 (with timer) series; temperature-based speed – GTT-1 series; stepless 0-10 VDC or Modbus control – electronic EVS-1 series.

    Pros

    • Flow / pressure confirmation interlock
    • Relay output COM / NO / NC (230 VAC / 2 A)
    • Sinusoidal output voltage – quiet motor operation
    • TK motor protection
    • Remote switch-on / thermostat input
    • Unregulated 230 VAC / 2 A output
    • IP54 enclosure

    Cons / limitations

    • Step, not stepless control
    • Heavy weight (5.60 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
    • Flow sensor or pressure switch is not included

    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 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).
    • Relay output load – no more than 230 VAC / 2 A.
    • Design and coordinate the gas equipment interlock according to the gas equipment manufacturer's requirements and applicable rules.

    Quick selection guide

    5 A
    230 VAC
    Airflow monitoring
    TK
    IP54
    Suitable when you need:
    • a fan up to 5 A with an airflow confirmation interlock;
    • gas valve or actuator control only when airflow is present;
    • quiet sinusoidal voltage control.
    Check before use:
    • the motor rated current and whether it is voltage-controllable;
    • the contact type of the flow sensor or pressure switch;
    • the valve or actuator current (relay up to 2 A);
    • the ambient temperature (up to +35 °C).
    Important reminder: SFPR1-50L22 does not control EC fans or three-phase motors; the flow sensor is not included.

    FAQ

    How does the flow monitoring work?
    The contact of a flow sensor or pressure switch is connected to the FL terminals. If it closes within 60 s of start-up, the relay for the gas valve or actuator is switched on.
    What are the speed steps?
    110, 140, 170, 190 and 230 VAC plus an OFF position; other voltages can be selected by changing the internal wiring.
    Is the sensor included?
    No, the flow sensor or pressure switch is selected separately.
    Can it be controlled by a thermostat?
    Yes, the NC contact of a thermostat or remote switch is connected to the remote on input.

    Transformer fan motor speed controller with airflow-dependent gas valve interlock | TK | 5A | 230VAC | surface-mounted | IP54 | Sentera Controls | SFPR1-50L22

    Sentera SFPR1-50L22 – transformer fan speed controller with airflow monitoring, up to 5 A, 230 VAC, 5 steps 110–230 VAC, relay output for a gas valve, TK protection, 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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