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Switching Relays

WEHRLE direct-current-relays are used for the switching of high currents with small control-wire diameters and voltage drops. They are used for numerous applications.

We would be happy to assist you in finding the correct relay.

Technical terms for relays:

  • Pull-in voltage: Lowest value of the energizing voltage, by which the relay picks up.
  • Drop-out voltage of a relay: Energizing voltage by which the relay reverts to stationary position.
  • Nominal voltage: Voltage for which the relay is designed.
  • Electrical service life: Number of operations with which the relay may be in service electrically.
  • Continuous current: the current which a relay can carry with a given temperature.
  • Contact consumption: Material loss of the contacts as a result of evaporation due to the influence of an electrical arc.
  • Contact clearance: Clearance between the open contacts, measured at its narrowest point.
  • Contact type:

  • Contact voltage drop: Voltage drop between the relays connectors of the closed contact by a defined current power.
  • Contact power: Power through which the contacts touch.
  • Contact making material: WEHRLE offers relays in various contact making materials. Depending on the criteria, the following materials are available to WEHRLE: PdCu, AgNi, AgCuNi und AgSnO². 
    • PdCu: Suited for circuit pulsed operation. For example: Flasher Unit usage. Drawback: high contact voltage drop. 
    • AgNi/AgCuNi: Suited as a conduit for current and switch of ohmic and iductive loads for example: rear view mirror heating, motors and valves. 
    • AgSnO²: Suited for switching of capacitive and inductive loads. For example: H4 lamps, motors, glow plugs. Drawback: fluctuating contact voltage drops, through oxide.
  • Break contact: Relays contact which is closed when the relay is in a resting position and open when it is in a working position.
  • Contact-load voltage: Is the voltage between the contacts.
  • Relays contact where in a resting position the relay is open and in the working position the relay is closed.
  • Circuit of coil: Switching off results in induction voltage which may result in a disruption of the electrical system. In order to avoid or reduce this a circuit of the coil with a choice of resistor, diode or breakdown diode may be used. With this circuit, the switching time will be increased and as a result, the service life may be reduced. Therefore, it is necessary to examine the application.