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Lock out relay?

blackoakbob
blackoakbob Member Posts: 248
the info I was looking for Mike T. I will measure the resistance of the contactor coil and try to find an RBM relay that is greater. I do have a diagram as I remember this being used back in the late 70's in Carrier a/c units.Thanks, best regards, blackoakbob

Comments

  • blackoakbob
    blackoakbob Member Posts: 248
    Lock out relay...

    I'm wondering if I can use any relay for a lock out relay or if the coil has to be special. They used to call them impedance relay? The application is to have the coil run in parallel with a limit control or contact and the normally closed contacts of the relay in series with the limit contacts to hold open the circuit when the limit switch opens and require a break in the operating control to reset the locked out limit circuit. To further explain my application I have a geo thermal heat pump heating a buffer tank with a parallel gaas modcon boiler on a utility controlled dual heat setup. The utility will open a dry contact which opens the 24v line to the compressor contactor locking out the circuit and as the temp in the buffer tank drops the limit switch in the tank starts the boiler, it runs until the limit switch in the buffer tank or the thermostat statisfies, breaking the cicuit and allowing the it to cycle when the utiltiy returns control.
    Thank you in advance. Best regards,
    blackoakbob
  • Tom Hopkins
    Tom Hopkins Member Posts: 545


    Well, I don't know anything an impedance relay, so I googled the topic. There was more information (of course) than I could digest, but in answer to your question, it sure looks like it's not the same thing as an ordinary relay!
  • Empire_2
    Empire_2 Member Posts: 2,343
    Hello Bob...

    Generally it depends on what you are controlling. If your normally active circuit has multiple loads, (24vac)you can almost get away with any pilot duty relay. If you are only using 1 other load ,...other than the ISO relay, then you would want the ISO relay to have a higher VA rating or resistance rating than the main parallel circuit load. Remember Electricity, Like water takes the path of least resistance.

    This may help.

    Mike T.
  • Empire_2
    Empire_2 Member Posts: 2,343
    Hello Bob...

    Generally it depends on what you are controlling. If your normally active circuit has multiple loads, (24vac)you can almost get away with any pilot duty relay. If you are only using 1 other load ,...other than the ISO relay, then you would want the ISO relay to have a higher VA rating or resistance rating than the main parallel circuit load. Remember Electricity, Like water takes the path of least resistance.

    This may help..................Sorry For some reason I cannot forward the diagram I drew up for you.

    Mike T.
  • Empire_2
    Empire_2 Member Posts: 2,343
    Exactly what I was reffering to:

    I to, had my first experience with the CARRIER,..."Lock Out" relay and what this was designed to do was give you nothing more than an ALARM and or A lOCK OUT SITUATION. Only way to reset it was to break the circuit and or let it do what it was designed to do, letting you or the customer know that there was a problem. But,...Either way the limit trip in your case has to clear or reset to energise the origional operating circuit.

    Mike T.
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