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  1. #1
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    Testing with a Megger



    Hi Guys,

    I've been told a few different ways to do this by the blokes I work with.

    Can anyone confirm to me though the correct and safe way to test single and three phase motors using a megger. Either balance testing (which I believe is using the ohms setting) or insulation testing (using the volts setting).

    Many thanks in advance,

    Bash



  2. #2
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    Re: Testing with a Megger

    To megger test a 3-phase motor with a 1000volt megger tester:

    Testing to earth

    a) Switch off the circuit breaker.

    b) Connect black megger test probe to earth. Check for ground continuity, to a terminal box bolt (this is check for good ground connection)

    c) With black probe still connected to ground, connect the red test probe to a motor terminal. Push test button. Insulation resistance should indicate 1 meg-ohm or more.

    d) Repeat test on remaining motor terminals

    Testing between windings

    e) Disconnect all line connections & remove bridging links.

    f) Identify the individual winings

    g) Connect black probe to one winding, test with red probe to other windings. Again, insulation resistance should indicate 1 meg-ohm or more.

  3. #3
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    Re: Testing with a Megger

    g- ur only testing resistance so the reading will be in ohms- in 3 phase they should be equal in a single phase compressor they will be different according to start and run windings

  4. #4
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    Re: Testing with a Megger

    An important note, never ever megger a compressor when it is under vacuum!!

  5. #5
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    Re: Testing with a Megger

    That can happen?

  6. #6
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