1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Elec Eng AC 3 Phase Symmetrical Components Q - Phase to Fault question

  1. Oct 7, 2014 #1
    Hello again,

    I've got another question that involves symmetrical components, this time I've attempted it.

    The Question follows:

    1. In a 3 phase circuit with resistance earthed and neutral and earth fault in phase “A” which produces a fault current of 800 amps.

    Load currents may be taken as zero.

    What will be the positive, negative and zero sequence currents in this system?


    I have Ia = 800 for Phase A, Ib = 0 and Ic = 0 and I assume this is a Phase-to-earth fault

    According to this source https://www.selinc.com/WorkArea/DownloadAsset.aspx?id=100688, when Phase B and Phase C is zero (as suggested by "Load currents may be taken as zero"): the zero,
    positive and negative sequence are all 1/3Ia. It also says that when an phase to earth fault happens in Phase A: Phase B and Phase C can be assumed to have no current anyway.

    Therefore Ia = 800A and I0, I1, I2 = 267A. Is my answer and thought process right?

  2. jcsd
  3. Oct 8, 2014 #2
    Yes, it's correct
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted