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  • New item   Interface relay | 4CO | 7 A | coil 24 V AC | plug-in | Finder 55.34.8.024.0040

    Interface relay | 4CO | 7 A | coil 24 V AC | plug-in | Finder 55.34.8.024.0040

    Code: 55.34.8.024.0040
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    Price 4.33 € VAT incl.
    ( 3.58 € VAT excl. )

    Finder 55.34.8.024.0040 – interface relay with 4CO contacts (7 A) and 24 V AC coil. For control signal isolation, contact multiplication and control of contactor and valve coils in automation panels.

  • Product description

    Interface relay | 4CO | 7 A | coil 24 V AC | plug-in | Finder 55.34.8.024.0040

    Finder 55.34.8.024.0040 is an interface relay with a 24 V AC coil and 4CO changeover contacts rated 7 A. It receives a weak control signal and switches another circuit through a galvanically isolated contact.

    Key point:
    A relay with a 24 V AC coil fits where the control voltage comes from a transformer – heating, ventilation and air conditioning (HVAC) controllers, door and gate automation. No separate 24 V DC power supply is needed.
    Contacts
    4CO (4PDT)
    Rated current
    7 A / 250 V AC
    Coil voltage
    24 V AC
    Indication
    lockable test button and mechanical indicator

    Operating principle

    The relay plugs into a suitable socket on a DIN rail (or is soldered to a PCB). The control voltage is applied to coil terminals A1–A2.

    When current flows through the coil, the electromagnet pulls the armature and switches the contacts: the common contact (COM) leaves NC and closes to NO. When the control voltage drops, a spring returns the contacts to their initial position.

    Coil and contact circuits are galvanically isolated, so a weak control signal safely controls a circuit at another voltage.

    Why choose Finder 55.34.8.024.0040?
    Finder 55.34 – four changeover contacts rated 7 A in one housing and a lockable test button with mechanical indicator: during commissioning the relay can be operated manually without changing the circuit.

    Technical specifications

    Product type Interface (control) relay
    Manufacturer / code Finder 55.34.8.024.0040
    Series Finder 55 (55.34)
    Coil voltage 24 V AC
    Coil power 1.5 VA; 190 Ω; 53 mA
    Operate / release voltage 19.2…26.4 V; drop-out 0.2 Un
    Contacts 4CO (4PDT)
    Contact material AgNi
    Rated current 7 A (peak 15 A)
    Max. switching voltage 250 V AC
    Rated load AC1 1750 VA
    Load AC15 350 VA (230 V AC)
    DC1 breaking capacity 7 A / 24 V · 0.5 A / 110 V · 0.25 A / 220 V
    Mechanical life 20 × 10⁶ cycles
    Electrical life 150 × 10³ cycles (AC1)
    Insulation coil–contacts 2000 V AC; 4 kV (EN 61810-1)
    Operate / release time 9 ms / 5 ms
    Operating temperature −40…+85 °C
    Mounting plug-in, socket-mounted
    Indication lockable test button and mechanical indicator
    Protection class RT I
    Compatible sockets Finder 94.04 / 94.P4 / 94.54 / 94.74 (DIN), 94.14 (PCB)
    Accessories 99.02, 86.30, 094.91.3, 094.71

    Main functions

    • Galvanic isolation – the control circuit is protected from load circuit disturbances.
    • 4CO contacts – one signal can control a load and return a status signal.
    • Signal amplification – a weak PLC or controller output switches a 7 A load.
    • Plug-in mounting – fast replacement without disconnecting wires.
    • Voltage conversion – control at one voltage, load at another (e.g. 24 V → 230 V).

    Where is it used?

    • Amplification of HVAC controller outputs
    • Control of heating boilers and pumps
    • Gate and door automation
    • Control of ventilation dampers and actuators
    • Control from a 24 V AC transformer
    • Contact multiplication in control circuits
    • Building automation panels

    Use by need

    HVAC installer.
    Control straight from a 24 V AC transformer, no extra power supply.
    Building automation specialist.
    Contact multiplication and circuit isolation in control panels.
    Gate automation installer.
    Extra contacts for signalling or lighting control.

    Practical application

    If an HVAC controller with a 24 V AC output has to start a circulation pump and switch on an indicator lamp, the controller output connects to the relay coil, while the pump contactor and the lamp go through separate relay contacts.

    Pros

    • Galvanic isolation of control and load circuits
    • Plug-in mounting – fast replacement
    • Standard contact numbering
    • Wide choice of sockets and accessories
    • 4CO – four independent circuits from one signal
    • Lockable test button and mechanical indicator

    Cons / limitations

    • No LED – visual indication requires a 99.02 socket module
    • Limited DC breaking: 0.5 A at 110 V DC
    • Not a protective device – does not protect against overload or short circuit
    • Inductive loads need a suppression circuit (diode, RC or varistor)
    • Use a contactor for motors and large loads

    Safety and installation notes

    • Disconnect the supply before installation and verify absence of voltage.
    • Check coil voltage and type (AC/DC) – a wrong coil will not operate or will burn out.
    • Suppress inductive loads (coils, valves) with a diode (DC) or RC circuit / varistor (AC).
    • Protect the contact circuit with a circuit breaker or fuse.
    • Do not exceed rated current and voltage; in DC circuits allow for the lower breaking current.

    Quick selection guide

    4CO
    7 A / 250 V AC
    24 V AC
    socket Finder 94.04
    Suitable when you need:
    • control from a 24 V AC transformer or HVAC controller
    • to multiply control contacts
    • to isolate control and load circuits
    Check before use:
    • coil voltage and type (AC or DC)
    • load type and current (resistive, inductive, LED)
    • that you have a compatible socket: Finder 94.04 / 94.P4 / 94.54 / 94.74 (DIN), 94.14 (PCB)
    Important reminder: an interface relay is not a protective device. It does not protect against overload or short circuit, and motors and large loads require a contactor.

    FAQ

    Do I need a socket?
    Yes, a plug-in relay needs a socket for DIN rail mounting; compatible: Finder 94.04 / 94.P4 / 94.54 / 94.74 (DIN), 94.14 (PCB).
    Can the coil be powered at another voltage?
    No, the coil must match the control voltage and type – 24 V AC.
    Is it suitable for driving a contactor coil?
    Yes, that is one of the most common uses; a suppression circuit is recommended.
    Can a motor be connected directly?
    No, connect the motor through a contactor with thermal protection; the relay drives the contactor coil.
    What does 4CO mean?
    It is the number of changeover contact sets; each has COM, NC and NO.
    Do you help with selection?
    Yes, send us a diagram or equipment list – we will select relays, sockets and contactors.

    Interface relay | 4CO | 7 A | coil 24 V AC | plug-in | Finder 55.34.8.024.0040

    Finder 55.34.8.024.0040 – interface relay with 24 V AC coil and 4CO contacts 7 A, for signal isolation, contact multiplication and control of contactors and valves in automation and electrical panels.

    Published: 2026-11-05 · Data verified against the manufacturer datasheet: 2026-11-05

    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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