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Thread: system grounding

  1. #21
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    Quote Originally Posted by GoldDigger View Post
    So would it be fair to say that the utility designation of 4160/2400 is just indicating that it can be used with either a single ended 2400 source or with a 4160Y/2400 source as long as in either case it is connected across a 2400V potential?
    In the second case that would require an L-N connection to the wye source.
    If the transformer has two insulated primary bushings, it could also be connected line to line IF the line to line voltage is 2400.
    Not working for a POCO, I would agree.
    Just because you can, doesn't mean you should.

  2. #22
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    Quote Originally Posted by jim dungar View Post
    Not working for a POCO, I would agree.
    I am not a lawyer either....

  3. #23
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    Usually they will read, "4160gy/2400 or "4160grndy/2400" if it's a single bushing unit. Obviously you can use a two bushing unit connected L-N, but not a single bushing connected L-L (where L designates an ungrounded conductor). I would think these days a two bushing 2400 transformer is mostly extinct except for old units, as utilities have converted these systems to 4160y
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  4. #24
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    That would be gy or grndy as in grounded wye, I assume.
    The NEC designation 4160Y/2400 does not tell us one way or the other about whether it is a grounded system.

  5. #25
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    Quote Originally Posted by robeward View Post
    ...
    Correct. Reverse wiring this one. Just how they are designated. I believe there is an ANSI standard governing this designation.
    ...
    And your output will be 2400V. Not 4160V, right?
    I'll never get there. No matter where I go, I'm always here.

  6. #26
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    Quote Originally Posted by robeward View Post
    ... I believe there is an ANSI standard governing this designation.
    ...
    IEEE Std. C57.12.00 (ftp://mail.sptc.com.sa/Specs&Standar...12.00-2010.pdf)

    See Tables 8 and 9.
    I'll never get there. No matter where I go, I'm always here.

  7. #27
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    Quote Originally Posted by Smart $ View Post
    IEEE Std. C57.12.00 (ftp://mail.sptc.com.sa/Specs&Standar...12.00-2010.pdf)

    See Tables 8 and 9.
    That is good info, thanks.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  8. #28
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    Quote Originally Posted by Smart $ View Post
    Remove the bonding strap connected to PRI X2 in the step up transformer. Connect it to SEC H2 along with the secondary grounded conductor (currently depicted as connected to enclosure on right side).

    BTW, the secondary is simply a single voltage, assuming 4160V. It is definitely not 4160GY/2400, as this would be a 3Ø wye configuration.
    I fully understand and agree with the "Remove the bonding strap connected to PRI X2 in the step up transformer".

    However I do not understand: "Connect it to SEC H2 along with the secondary grounded conductor (currently depicted as connected to enclosure on right side)". I would not connect that PRI X2 to anything. Maybe you might be able to explain so I can understand.

  9. #29
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    Quote Originally Posted by dionysius View Post
    I fully understand and agree with the "Remove the bonding strap connected to PRI X2 in the step up transformer".

    However I do not understand: "Connect it to SEC H2 along with the secondary grounded conductor (currently depicted as connected to enclosure on right side)". I would not connect that PRI X2 to anything. Maybe you might be able to explain so I can understand.
    I did not know he was using an oil-immersed transformer [with internal factory bondings] at the time I wrote that. Yea, de signs where dere but dey just flew right over me head. I was thinking dry transformer. Alas!

    Remove the bonding strap completely and ignore all else in my earlier post.
    I'll never get there. No matter where I go, I'm always here.

  10. #30
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    I am still getting through all the responses. Sorry the email notifications quite coming in.

    Quote Originally Posted by winnie View Post
    Essentially yes. If you put a meter between the neutral of the wye and the center point of the single phase transformer, you would measure a pretty stiff 138V. Connecting these two points would cause large circulating currents in the transformer(s), and if you ground these two points the current flow would depend on the ground electrode resistance.

    My assumption is that the single phase transformer is most commonly used for step down operation, where the secondary is supposed to be grounded by the strap...but when this transformer is used for step up operation the strap needs to be removed.

    -Jon
    Yes most commonly used for step down. Can you explain how you came up with 138v please?

    Quote Originally Posted by electrofelon View Post
    Robeward,

    May I inquire into the application? Is this a step up because of a long wire run?
    Exactly right. Long cable run. When we buy them we tell cooper when we are going to use it for step up operation but the strap seems to be installed regardless.

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