×
Follow Us
Results 1 to 4 of 4

Transformer Primary Fault Current

 Jump to latest post
    #1
  1. kchenoweth is offline Junior Member Pro Subscriber
    Join Date
    May 2018
    Posts
    3
    Reputation

    Transformer Primary Fault Current

    The question states:

    1000kVA 34.5kV to 480V secondary transformer 5% imp. Apply 480V to primary side and ground secondary. What is primary fault current?

    My calculations come up to 8.0655A, but it says the correct answer is 4.65A. Am I doing something wrong?

  2. #2
  3. Join Date
    Jan 2015
    Posts
    2
    Reputation
    Quote Originally Posted by kchenoweth View Post
    The question states:

    1000kVA 34.5kV to 480V secondary transformer 5% imp. Apply 480V to primary side and ground secondary. What is primary fault current?

    My calculations come up to 8.0655A, but it says the correct answer is 4.65A. Am I doing something wrong?

    Looks like a missing square root of 3

  4. #3
  5. Join Date
    Feb 2018
    Posts
    11
    Reputation
    wpuld you like to share the calculation?

  6. #4
  7. STXERS17 is offline Junior Member Pro Subscriber
    Join Date
    Jul 2017
    Location
    South Texas
    Posts
    7
    Reputation
    Quote Originally Posted by dharmikpandya0 View Post
    wpuld you like to share the calculation?
    This is what I got:

    1) Find Ipri at 345000V:
    Ipri = (kva x 1000)/(V x 1.732) = 1000000/(34500 x 1.732)=16.32 Amps

    2) Find Ipri at 480V:
    34500/16.73=480/I
    Ipri=(480 x 16.32)/34500=0.23 Amps

    3) Find Isc at 480V:
    Isc=I/Z ≫ Isc=0.23/0.05=4.6 Amps

Subscribe

Share this thread

Related Topics

  1. Primary Current Injection instantenous Pickup
    By changeabilities in forum Electrical Testing Talk
    Replies: 15
    Last Post: February 26, 2021, 11:50 AM
  2. Replies: 12
    Last Post: July 28, 2020, 08:27 AM
  3. Primary Current Injection Test
    By changeabilities in forum Electrical Testing Talk
    Replies: 4
    Last Post: August 12, 2018, 08:17 AM
  4. Primary current injection 138kV breaker with bushing CT's
    By david2458 in forum Electrical Testing Talk
    Replies: 1
    Last Post: April 12, 2018, 05:27 AM
  5. Easy way to calculate transformer fault current
    By SecondGen in forum Electrical Testing Talk
    Replies: 0
    Last Post: June 11, 2015, 06:40 PM

Tags for this Thread

Follow us


Explore TestGuy


NETA Certification Training


NICET Electrical Power Testing


Help and Support




You are viewing the archives. Enjoy new features and join the conversation at wiki.testguy.net