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Thread: zig zag transformer

  1. #61
    Join Date
    Jun 2004
    Location
    Cherry Valley NY, Seattle, WA
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    3,178
    Quote Originally Posted by Sahib View Post
    David & electrofelon: Would you mind giving your comments on the paper in post#45. That may clarify the matter a bit.
    Sahib, that paper really isn't applicable. These inverters take a neutral and it is grounded. That's the way we do things here in the us. There are 2 options: 1. The zig zag is for harmonics. 2. The zig zag is there to satisfy a utility requirement (and possible misapplied).

    I guess a 3rd option is that the designed put the zig zag in for a redundant system groundING means in case the MBJ was lifted, neutral failed, etc.... IMO that would be ridiculous.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  2. #62
    Join Date
    Jan 2016
    Location
    PA
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    3,762
    Sketch the 0 seq network diagram
    the Yg:Yg xfmr makes it interesting (seems like a bad option imo)
    phase shift?
    both sources util & pv will supply sec gnd fault i
    Looks like they are trying to give each source a rtn path?
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  3. #63
    Join Date
    Feb 2013
    Location
    India
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    2,077
    Quote Originally Posted by Ingenieur View Post
    both sources util & pv will supply sec gnd fault
    Looks like they are trying to give each source a rtn path?
    The issue for the POCO is a solidly grounded PV system could make the protection coordination ineffective by its contribution to fault current. So the POCO (in US, of course)usually demands an effective grounding. In some cases, however, POCO may allow solid grounding (as in OP case with solidly grounded zigzag transformer) if the PV system trips fast in case of POCO distribution line fault.

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