×
Follow Us
Results 1 to 3 of 3

What is the proper formula for 3 phase turns ratio?

    #1
  1. Join Date
    Jul 2020
    Posts
    7
    Reputation

    What is the proper formula for 3 phase turns ratio?

    What is the turns ratio for a delta wye 138000/12470 XFMR. What is the proper formula? Thanks

  2. #2
  3. Kalbi_Rob's Avatar
    Kalbi_Rob is offline Experienced Member Pro Subscriber
    Join Date
    Feb 2018
    Location
    Jacksonville, NC
    Posts
    290
    Reputation
    Quote Originally Posted by Js20981 View Post
    What is the turns ratio for a delta wye 138000/12470 XFMR. What is the proper formula? Thanks
    First step is to only use phase to ground voltages.
    For Delta, Line-to-Line = Phase-to-Ground voltages.
    For Wye, SQRT(3) * Line-to-Line = Phase-to-Ground voltages. Vp=12470/SQRT(3)=12470/1.732=7199.8V

    TTR=138000V/7200V=~19.166

    Math should be correct minus rounding errors.

  4. #3
  5. southbury's Avatar
    southbury is offline
    Neta 4 Tech
    Junior Member
    Join Date
    Jul 2017
    Posts
    14
    Reputation
    as the previous post already explained
    These questions are hard to answer.

    Even NETA is vague on the exams.

    Given 138,000 to 12470
    They do not tell you the connections( I protested these questions)



    138,000 probably a line to line voltage so you would assume a delta
    12470 probably a wye voltage. 12470/square root 3=7199.56=7200

    138,000/7200=19.1666

Subscribe

Share this thread

Related Topics

  1. What is the turns ratio?
    By franko26 in forum NETA Level 2 Exam
    Replies: 23
    Last Post: February 14, 2022, 10:36 AM
  2. Dry Tranformer Turns Ratio
    By shamimkhan in forum Electrical Testing Talk
    Replies: 2
    Last Post: January 18, 2018, 10:22 AM

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