×
Follow Us
Results 1 to 5 of 5

Utility vs. Customer Phase Rotation - Level III Test Question (Recent 7/16)

 Jump to latest post
    #1
  1. Join Date
    Jul 2016
    Posts
    3
    Reputation

    Utility vs. Customer Phase Rotation - Level III Test Question (Recent 7/16)

    Thoughts on this?

    A utility defines their horizontal bus at the customer point as ABC left to right facing the customer with ABC rotation. The customer defines their buses as ABC left to right facing the utility but with CBA rotation. For a first time connection the customer has to:

    A: Swap A & B phases and leave phase sequence alone
    B: Swap B & C phases and leave phase sequence alone
    C: Leave phasing alone and change phase sequence to ABC
    D: leave phasing and phase sequence alone.

    I guessed D because and don't know if I'm right. Is there a proper procedure here? Explain if possible.

  2. #2
  3. Join Date
    May 2016
    Posts
    7
    Reputation
    I would also choose D. Utility is Rotating A-B-C left to right, so if customer is wired C-B-A then the rotation would naturally be C-B-A left to right. What gets confusing is which side of the line you are looking at. They try to trick you by saying "facing the utility" or "facing the customer". It's easier if you draw it out and flip it around.

    A-B-C (Utility)
    --------
    C-B-A (Customer)

  4. #3
  5. Join Date
    Jan 2017
    Posts
    1
    Reputation
    I took the exam last Friday 1-27-17 and answered this question with D also.

  6. #4
  7. Join Date
    Feb 2016
    Posts
    6
    Reputation
    Quote Originally Posted by BRAD2121 View Post
    Thoughts on this?

    A utility defines their horizontal bus at the customer point as ABC left to right facing the customer with ABC rotation. The customer defines their buses as ABC left to right facing the utility but with CBA rotation. For a first time connection the customer has to:

    A: Swap A & B phases and leave phase sequence alone
    B: Swap B & C phases and leave phase sequence alone
    C: Leave phasing alone and change phase sequence to ABC
    D: leave phasing and phase sequence alone.

    I guessed D because and don't know if I'm right. Is there a proper procedure here? Explain if possible.
    D is the correct answer. If you read through A,B, and C choices they are all having the same effect on the sequence/phasing. Basically they are all the same answer with different means of getting there.

  8. #5
  9. Join Date
    Aug 2021
    Posts
    10
    Reputation
    Heres another way to look at it visually as well that helps see the rotation swap. Click image for larger version. 

Name:	phasors.jpg 
Views:	4 
Size:	450.0 KB 
ID:	552

Subscribe

Share this thread

Related Topics

  1. Saturation test of a 1500/5 multi-ratio CT
    By Tseppish in forum Electrical Testing Talk
    Replies: 11
    Last Post: August 4, 2021, 10:21 AM
  2. Replies: 9
    Last Post: August 16, 2018, 02:28 PM
  3. Insulation resistance test set question
    By mkennedyShermco in forum NETA Level 4 Exam
    Replies: 2
    Last Post: June 10, 2018, 12:52 PM
  4. Replies: 2
    Last Post: February 2, 2016, 01:35 PM
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