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Thread: system grounding

  1. #1
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    system grounding

    please see attached image. both transformers are pad mount. as of now i am assuming the utility is grounding their transformer as shown. I am not sure what standard practice is. assuming they do would their be any issues with the grounding as shown on the step up transformer?

    my primary concern is the removable bonding strap that comes pre-installed on the transformer as shown. if it is left on will there be any current between the ground rods through the ground? i can't convince myself if there is a complete circuit with voltage or not. a grounded conductor will not be connected between the two transformers.
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  2. #2
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    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.
    Last edited by Smart $; 02-28-17 at 08:18 PM.
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  3. #3
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    I've never seen a set up like this.
    I did go to Duke Energy
    https://www.duke-energy.com/_/media/...nual.pdf?la=en
    Pages 85, 86, 87.
    If you are even thirsty, you are two quarts low.

  4. #4
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    Quote Originally Posted by Smart $ View Post
    Remove the bonding strap connected to PRI X2 in the step up transformer.
    Absolutely.

    In the 3-phase wye transformer the voltage L-G is 277V. While, the single phase transformer primary winding arrangement the voltage L-G is only 240V.
    Just because you can, doesn't mean you should.

  5. #5
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    Quote Originally Posted by jim dungar View Post
    Absolutely.

    In the 3-phase wye transformer the voltage L-G is 277V. While, the single phase transformer primary winding arrangement the voltage L-G is only 240V.
    And the above voltage difference implies that the neutral of the wye is at about 138V relative to the neutral of the single phase coil. You will either see high current or high voltage between the two 'grounds'.

    -Jon

  6. #6
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    Quote Originally Posted by Smart$

    BTW, the secondary is simply a single voltage, assuming 4160V. It is definitely not 4160GY/2400, as this would be a 3Ø wye configuration.
    Note that is how these single phase transformers are typically designated. The transformer high side is 2400, line to neutral of a 4160 wye system.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  7. #7
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    Quote Originally Posted by electrofelon View Post
    Note that is how these single phase transformers are typically designated. The transformer high side is 2400, line to neutral of a 4160 wye system.
    As drawn there is no neutral. So unless the OP depicts it incorrectly, Smart$ is right (as usual).


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  8. #8
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    Quote Originally Posted by electrofelon View Post
    Note that is how these single phase transformers are typically designated. The transformer high side is 2400, line to neutral of a 4160 wye system.
    Quote Originally Posted by Strathead View Post
    As drawn there is no neutral. So unless the OP depicts it incorrectly, Smart$ is right (as usual).
    Electrofelon is correct if the OP is reverse wiring a typical pole pot. It's just how MV equipment is designated.
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  9. #9
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    Quote Originally Posted by Strathead View Post
    As drawn there is no neutral. So unless the OP depicts it incorrectly, Smart$ is right (as usual).
    Many of those transformers are a single bushing on one side of the HV coil and bonded to the case on the other, so at very least we can call it a grounded conductor whether it is a true neutral or not.

  10. #10
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    Quote Originally Posted by kwired View Post
    Many of those transformers are a single bushing on one side of the HV coil and bonded to the case on the other, so at very least we can call it a grounded conductor whether it is a true neutral or not.
    Unless I am mistaking what is being said or terminology, it would be a grounded conductor, but not a neutral and the reason is exactly why the code uses the terms the way they do. A neutral would have to be a tap point in the center of the transformer coil as drawn. I don't see how it could be referenced as dual voltage when there is not a center tap. if this is just a habit which it seems like electrofan and smart$ are saying then it is a bad habit. This is all dependent on whether I actually understand what smart$ was saying which is very possibly a false assumption.


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