Question about trip breakers

Discussion in 'General Electronics Chat' started by saruji, Apr 14, 2013.

  1. saruji

    Thread Starter New Member

    Oct 18, 2011
    14
    0
    hello,

    I have a situation where a large set of electric motors are connected to a power cabinet. In the power cabinet is a breaker for each motor. I've got two motors(next to each other) that are turning off at the same time that are on two separate breakers (next to each other). I keep resetting the breakers, but after a few short seconds one and then the other breaks again, or sometimes both break at the same time. I've forced these to stay open using a piece of wood, my question:

    a) How dangerous or likelyhood of overload or fire? (this is very temporary)
    b) Why would they both be breaking at the same time?
    c) Any leads on how to proceed with troubleshooting?

    thank you,

    Background: sophmore year EE student. (This is not a test/homework related question)

    My guess is that it is a bad breaker, but how can I check? Also there is a surge suppressor on the breaker could it have somethign to do with this?
     
    Last edited: Apr 14, 2013
  2. #12

    Expert

    Nov 30, 2010
    16,257
    6,759
    Very dangerous. Measure the current with your clamp style amp meter.
    What? You don't have one?
    Get one.
    $40 is a lot cheaper than burning up the motors or burning down the building.
     
  3. saruji

    Thread Starter New Member

    Oct 18, 2011
    14
    0
    Ok. I've removed the wooden holder an checked the current at the load. 1 outlet is 1 amp and the other 10 mA. There is a trip lever and an off/reset button. On the one with 10mA the trip level is stuck on trip while the other is in the normal position. After adjusting this lever the breaker(manually) the breaker holds before the lever goes back to trip and the breaker trips both agai , but this time much longer. Advice on how to proceed?

    Could honestly not thank enough.
     
  4. saruji

    Thread Starter New Member

    Oct 18, 2011
    14
    0
    Forcing the breaker, one of the motors ( the one pulling only 10 mA) is very very hot now.
     
  5. saruji

    Thread Starter New Member

    Oct 18, 2011
    14
    0
    Anyone point me in a direction for a possible solu?
     
  6. vortmax

    Member

    Oct 10, 2012
    103
    18
    This sort of stands out as a big problem....so stop doing that.

    I am sort of confused by your layout and what all is actually happening. How did you 'adjust' the breaker? How about some diagrams or photos?

    Since the motor is getting hot, I would first suspect a short in the coil. Pull it and check it.
     
  7. tinkerman

    Member

    Jul 22, 2012
    136
    34
    10 ma?? What sort of motor is that? Post more information, pictures, drawings.
     
  8. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
    348
    Are these 3 phase motors? If so, check for voltage balance on all phases.
     
  9. #12

    Expert

    Nov 30, 2010
    16,257
    6,759
    Big motors don't use 10 milliamps (10 thousandths of an amp). We need you to get your units correct.
     
  10. saruji

    Thread Starter New Member

    Oct 18, 2011
    14
    0
    My units where correct. 10 x 10^-3 Amps or 10 mA
     
  11. saruji

    Thread Starter New Member

    Oct 18, 2011
    14
    0
    Yes that was it, I went back to the motor and notices a smell, removed the cover and saw that the coil was breaking(cracked) replaced an all is well now.

    Btw I adjusted the amount of current through the breaker. Thanks to everyone here. My apologies that my post was not accompanied by pictures and only amateur details.
     
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