User Tag List

Page 3 of 4 FirstFirst 1 2 3 4 LastLast
Results 21 to 30 of 39

Thread: Transformer Issue

  1. #21
    Join Date
    May 2003
    Location
    Leesburg, VA
    Posts
    7,108
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    No load current is 12, 8, 7, which seems unusual as well, normally we see where the two outside coils are high compared to the center winding.

    I have pulled my load banks for another job I' will have to see if the customer will pay for a second test.
    Brian John
    Leesburg, VA

  2. #22
    Join Date
    Feb 2013
    Location
    India
    Posts
    2,713
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    As you already meggared and found insulation resistance of transformer okay, the circulating ground current is probably inductive and abnormal. Why not ask the manufacturer for a replacement?

  3. #23
    Join Date
    May 2003
    Location
    Leesburg, VA
    Posts
    7,108
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    The UPS manufacturer is looking into this issue. I am involved as a subcontractor because we offer electrical testing and often are hired to look into unusual electrical issues.
    Brian John
    Leesburg, VA

  4. #24
    Join Date
    Jun 2003
    Location
    NE (9.06 miles @5.9 Degrees from Winged Horses)
    Posts
    11,229
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by brian john View Post
    ...unusual electrical issues.
    Well it sounds like you found one
    Tom
    TBLO

  5. #25
    Join Date
    May 2003
    Location
    Leesburg, VA
    Posts
    7,108
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    The transformer was manufactured in India, I am going to attempt to reach someone there for some insight.
    Brian John
    Leesburg, VA

  6. #26
    Join Date
    Apr 2009
    Location
    Clarkesville, Georgia
    Posts
    2,385
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by brian john View Post
    The transformer was manufactured in India, I am going to attempt to reach someone there for some insight.
    Sahib?
    Dave Ruth

  7. #27
    Join Date
    Feb 2013
    Location
    India
    Posts
    2,713
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by readydave8 View Post
    Sahib?
    No. This OP query is not answered by us till date.

    Quote Originally Posted by brian john View Post
    No load current is 12, 8, 7, which seems unusual as well, normally we see where the two outside coils are high compared to the center winding.

  8. #28
    Join Date
    Dec 2012
    Location
    Placerville, CA, USA
    Posts
    20,296
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by brian john View Post
    No load current is 12, 8, 7, which seems unusual as well, normally we see where the two outside coils are high compared to the center winding.

    I have pulled my load banks for another job I' will have to see if the customer will pay for a second test.
    A Megger test of either a motor or a transformer will detect a line to ground (i.e. line to frame) short inside the windings, bit cannot detect a turn to turn short buried within the winding.
    A turn to turn short in one winding will act like an additional load winding on the magnetic circuit in question and will add a resistive component to the current measured for that winding. Depending on whether it is a single or multiple turn short and just what the resistance of the short is, the resulting current could cause asymmetric current and extra heating and maybe noise or could cause enough extra current to trip OCPD.
    You can look at it as an autotransformer with a shorted secondary connection.

  9. #29
    Join Date
    Jan 2008
    Posts
    9,708
    Mentioned
    0 Post(s)
    Tagged
    1 Thread(s)
    Quote Originally Posted by GoldDigger View Post
    A Megger test of either a motor or a transformer will detect a line to ground (i.e. line to frame) short inside the windings, bit cannot detect a turn to turn short buried within the winding.
    A turn to turn short in one winding will act like an additional load winding on the magnetic circuit in question and will add a resistive component to the current measured for that winding. Depending on whether it is a single or multiple turn short and just what the resistance of the short is, the resulting current could cause asymmetric current and extra heating and maybe noise or could cause enough extra current to trip OCPD.
    You can look at it as an autotransformer with a shorted secondary connection.
    But his voltage was good.
    BB+/BB=?

  10. #30
    Join Date
    May 2003
    Location
    Leesburg, VA
    Posts
    7,108
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Understand but a Turn Ratio Test should ascertain if a turns to turns short existed?
    Brian John
    Leesburg, VA

Posting Permissions

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