Page 3 of 9 FirstFirst 12345 ... LastLast
Results 21 to 30 of 81

Thread: Voltage Unbalance Reason

  1. #21
    Join Date
    Feb 2013
    Location
    India
    Posts
    2,406
    Quote Originally Posted by Ingenieur View Post
    +(vab = 25 + 175j) or 175/82-(vac = 25 - 175j) or 175/-82-(vbc = 0 + 350j) or 350/90= 0 + 0jsomething does not computeone machine in reverse rotationmessed up connectionsetc or some combination
    The generator voltage sequence is Vab, Vbc, Vca and their vector sum equals zero. But in your calculation Vac instead of Vca used. So perhaps reverse connection in one phase may also be a reason...

  2. #22
    Join Date
    Jan 2016
    Location
    PA
    Posts
    5,276
    using abc
    a 600/0
    b 600/-15
    c 600/15

    ab = 20+155j = 156/82
    bc = 0-310j = 310/-90
    ca = -20+155j = 156/98
    sum = 0

    no real change
    no idea what is going on
    The difference between genius and stupidity is that genius has its limits.

  3. #23
    Join Date
    Feb 2013
    Location
    India
    Posts
    2,406
    Quote Originally Posted by Ingenieur View Post
    using abc
    a 600/0
    b 600/-15
    c 600/15

    ab = 20+155j = 156/82
    bc = 0-310j = 310/-90
    ca = -20+155j = 156/98
    sum = 0

    no real change
    no idea what is going on
    One solution to the part of the riddle is the generator is ungrounded and so phase to neutral voltage may be anything, around 590V in the OP case. Another is if the actual voltage readings of the OP are taken, I think their vector sum may not be zero and so there may be a break in windings or one phase winding may be reverse connected and that is my stand.

  4. #24
    Join Date
    Oct 2009
    Location
    Austin, TX, USA
    Posts
    9,288
    Quote Originally Posted by JFletcher View Post
    I don't understand, if the neutral is kept floating, then aren't any line to neutral voltage readings meaningless?
    No. Phase and neutral voltage to ground readings are meaningless.

  5. #25
    Join Date
    Aug 2008
    Location
    San Francisco
    Posts
    677
    Quote Originally Posted by Ingenieur View Post
    using abc
    a 600/0
    b 600/-15
    c 600/15

    ab = 20+155j = 156/82
    bc = 0-310j = 310/-90
    ca = -20+155j = 156/98
    sum = 0

    no real change
    no idea what is going on
    The reason you can't make any sense of it is because the readings are meaningless on an ungrounded wye as others have stated over and over!
    Am I in shape?? I get plenty of exercise pushing my luck!!

  6. #26
    Join Date
    Jan 2016
    Location
    PA
    Posts
    5,276
    Quote Originally Posted by ATSman View Post
    The reason you can't make any sense of it is because the readings are meaningless on an ungrounded wye as others have stated over and over!
    you will get a reading thru capacative couple, because he DID get reading
    regardless, ph-n will not be 3x ph-ph
    The difference between genius and stupidity is that genius has its limits.

  7. #27
    Join Date
    Jul 2006
    Location
    SE USA as far as you can go
    Posts
    2,611
    The OP has left the discussion; so in other words it's all speculation after post #5.
    "Just because you're paranoid, doesn't mean they're not out to get you"

  8. #28
    Join Date
    Jan 2016
    Location
    PA
    Posts
    5,276
    we know a few things
    only occuring on 1 bus
    VLL = 150-300 (2 @ 150, 1 @ 300), VLN = 600, VLN ~ 2-4 x VLL
    we know what the ph ang must be to result in these magnitudes

    it is not cool for an op to make a post asking a question about an issue (especially an implausible one like this) and not providing feedback
    The difference between genius and stupidity is that genius has its limits.

  9. #29
    Join Date
    Apr 2009
    Location
    Williamsburg, VA
    Posts
    5,254
    Quote Originally Posted by Ingenieur View Post
    we know a few things
    only occuring on 1 bus
    VLL = 150-300 (2 @ 150, 1 @ 300), VLN = 600, VLN ~ 2-4 x VLL
    we know what the ph ang must be to result in these magnitudes

    it is not cool for an op to make a post asking a question about an issue (especially an implausible one like this) and not providing feedback
    That's been my main gripe with people posting questions on this form since its inception. People post the weirdest things, everyone brainstorms possible problems and solutions, and the o p rarely gets back to post what the problem was and how or if it was solved. C'est la vie...
    Electricians do it until it Hertz!

  10. #30
    Join Date
    Oct 2009
    Location
    Austin, TX, USA
    Posts
    9,288
    Quote Originally Posted by JFletcher View Post
    That's been my main gripe with people posting questions on this form since its inception. People post the weirdest things, everyone brainstorms possible problems and solutions, and the o p rarely gets back to post what the problem was and how or if it was solved. C'est la vie...
    But we have a lot of fun speculating and arguing, don't we?

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •