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Latching Relays

Discussion in 'General Electronics Chat' started by jinufrancis, Jun 10, 2013.

  1. jinufrancis

    Thread Starter New Member

    Jun 8, 2013
    Dear All,

    Can any one out there explain me about latching relays? I have a particular application of Hager EPN 515 being used in a two numbers sump pump circuit. I am having problem in troubleshooting the circuit.

    What is the purpose of a latching relay in a sump pump circuit? How to give the control command to this?

    Awaiting for all your replies...

    Many Thanks,

    Jinu Francis
  2. crutschow


    Mar 14, 2008
    Latching relays remain in the last commanded position without further input power. There are commonly two types:

    1. Those with a single coil and you reverse the voltage across the coil to change its state.

    2. Those with two coils. You alternately apply a voltage to one of the coils to change its state.

    The Hager EPN 515 appears to be a third, less common type which alternates its contact position with an impulse input.

    It likely is used in the sump pump circuit to control the motor by the limit switches. The top limit switch switches the relay to turn on the pump. The pump then stays on until the lower limit switch switches the relay to the other position, turning off the pump.

    My confusion is, that with the Hager impulse type relay, I don't know how you differentiate between an upper limit switch pulse and the lower limit switch pulse. :confused: