×
Follow Us
Results 1 to 2 of 2

PT Testing-Negative Tip Up

    #1
  1. Join Date
    Apr 2018
    Posts
    2
    Reputation

    PT Testing-Negative Tip Up

    We have been power factor testing oil filled potential transformers of different primary voltage levels and we have been getting some tests that are exhibiting negative tip up. It looks like this is due to the power factor being slightly worse at 2kv than at 10kv test voltage(at least thats how I understand it). Does anyone have any information on this or know why this happens?

  2. #2
  3. Join Date
    Aug 2015
    Posts
    14
    Reputation

    PT Testing negative tip-up

    Quote Originally Posted by merjer2005 View Post
    We have been power factor testing oil filled potential transformers of different primary voltage levels and we have been getting some tests that are exhibiting negative tip up. It looks like this is due to the power factor being slightly worse at 2kv than at 10kv test voltage(at least thats how I understand it). Does anyone have any information on this or know why this happens?
    Often times a negative tip up is due to the test results being carried out to the third place. The currents and capacitances at 2 kV and 10 kV should basicially be equal. The 10 kV watts may be ".128" while the 2 kV may be ".131" which would result in a negative tip up. Only .003 watts different so no concern. I have seen results in which both tests were performed at 2 kV and still received a negative tip-up with the watts being a little different.

    If this is a line to ground PT then normally 10 kV is not applied, except when only the H1 bushing is energized when the H2/H0 bushing is energized as that bushing is normally a smaller bushing. All other tests, including exciting current, at 2 kV or 5 kV.

Subscribe

Login or register to leave a reply!


Share this thread

Related Topics

  1. Negative power factor results on sf6 breaker
    By DLWood in forum Electrical Testing Talk
    Replies: 5
    Last Post: March 20, 2022, 10:09 AM
  2. When would you most likely use a negative sequence relay?
    By Tseppish in forum NETA Level 3 Exam
    Replies: 4
    Last Post: October 9, 2018, 04:41 AM
  3. Practice Test Question: Negative Sequence
    By EricGoetz92 in forum NETA Level 3 Exam
    Replies: 3
    Last Post: June 14, 2018, 07:36 PM
Follow us


Explore TestGuy


NETA Certification Training


NICET Electrical Power Testing


Help and Support