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More Questions about Protective Relays

  1. Aug 5, 2009 #1
    I am trying to protect two power sources from two generators from overcurrent, under/overvoltage, under/overfrequency,etc.
    There will be two generators running during the day and one running at night, I have double throw switches to switch the two breaker panels to run on one generator each or to share one generator. One generator's relay will run almost 24/7 and the other will cycle once per day.(Generators not ran in parallel.)

    I do not wish to use a shunt trip breaker connected to the protective relays for this purpose because I do not have an uninterruptable power supply. I was thinking of using a normally open contactor instead. I know a regular electromechanical relay will not last long in this application. What I am wondering is if it would be best to use a solid state relay or a mercury relay or something else for this application?

    The generators are 83 amp 120/208 volt 3 phase 24 KW.
  2. jcsd
  3. Aug 5, 2009 #2
    Since safety is obviously an issue, and there are just so many unanswered questions about your setup, I wouldn't rely on guesses found in a forum. To make a good decision here, you need a pro electrical engineer that has intimate knowledge of your setup and requirements.
  4. Aug 5, 2009 #3
    This is a home project I am just looking for something that will last and not get weak if I used electromechanical contactors continues rating and hold contacts the problem would be the risk of the coils becoming weak and failing this is all I am asking about. If the contactor fails, there is no immediate danger. I am an electrician.
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