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Thread: Back feeding a transfomer to test for a fault

  1. #1
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    Back feeding a transfomer to test for a fault

    Back feeding the secondary to test for a primary buss fault will only work for a wye grounded primary connection, correct? I can't see it working out for a delta primary but folks here would know better.

    Here is an example but nothing on the connections:

    https://www.youtube.com/watch?v=NkvaCbTWYwc
    I'm in over my head...

  2. #2
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    Quote Originally Posted by mbrooke View Post
    Back feeding the secondary to test for a primary buss fault will only work for a wye grounded primary connection, correct? I can't see it working out for a delta primary but folks here would know better.

    Here is an example but nothing on the connections:

    https://www.youtube.com/watch?v=NkvaCbTWYwc
    Didn't look at your link, but if you have delta secondary (secondary in that it is the derived voltage side) and one of the phases is at ground potential then it must be grounded, whether intentional or via fault.
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  3. #3
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    Quote Originally Posted by kwired View Post
    Didn't look at your link, but if you have delta secondary (secondary in that it is the derived voltage side) and one of the phases is at ground potential then it must be grounded, whether intentional or via fault.


    Not following you here- ground as in VT reference voltage distortion?
    I'm in over my head...

  4. #4
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    Quote Originally Posted by mbrooke View Post
    Not following you here- ground as in VT reference voltage distortion?
    If your "secondary" (which is the primary when not back fed) is 480 volt delta, and you energize it and find one line is at ground potential - that line is either intentionally bonded or is faulted, no different than an intentional corner ground system.

    If there is more than one fault - you will have fault current at some level.
    I live for today, I'm just a day behind.

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