Relay Locking

Discussion in 'General Electronics Chat' started by jagadish08, Feb 3, 2014.

  1. jagadish08

    Thread Starter New Member

    Feb 3, 2014
    Dear All,

    We are having 10 Normal relayes which are in energized condition with 24V DC and Output contact is with 110V AC. Since it is Emergency system and running plant we can't denergize the output. But we would like to hold the relay output contact in closed position for 1 to 2 hrs for some modification in Input side of relay. Willl that be possible.

    Relay Make : Potter & Brumfiled
    Relay Model No: KHS-17D13-120
  2. inwo

    Well-Known Member

    Nov 7, 2013
    If you can kill the power for some modifications, it may be possible.
    Feeding coils thru diode from aux. supply.

    If you have to ask, you may not be qualified to do it safely.
    Nor might anyone else!

    No matter how experienced the technician, it sounds risky.

    How serious would a mistake be? Shutting down the plant? Loss of life?
    mcgyvr likes this.
  3. MaxHeadRoom


    Jul 18, 2013
    One scenario to look at if just modifying the input (24v) side is to place a jumper across the points intended to be modified, leaving the present system active, make the modifications and then remove the jumper.
    Obviously this has to be done without jeapardizing the present safety aspect.
  4. ScottWang


    Aug 23, 2012
    If you can find the COM/NO pins of relay to hook up, or any two points are the same with COM/NO pins, maybe you can using two test hooks to make a shorted hook and use them to shorted COM/NO, and unplug the 24V relay, and then to do the modifications, but this is very dangerous, you should be very careful.

    I'm not sure the hook could flowing through enough current for the load.

    The test hooks.

    Another type of test hooks.
  5. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    I'm with inwo here.. If you have to ask you are NOT qualified to perform anything..

    And the solution is simple.. So you clearly aren't qualified. point blank..

    Maybe that relay is part of the Emergency Disconnect.. If so NO way in hell can you bypass that function..running plant or not.
  6. Externet

    AAC Fanatic!

    Nov 29, 2005
    There is a type of Potter & Brumfield latching relay that has a mechanism similar to a ball point pen. When energized changes latching.
    Unsure if I understand your application, but wanted to mention this just in case there is someone qualified to tamper with the system. Do not remember the relay part number. It has a white nylon clever mechanical latch inside.