Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Detection of inter-turn winding-short fault in 1-phase transformer

  1. Aug 14, 2013 #1
    Hi all,

    I have simulated (both in software and experimentally) inter-turn winding short-circuit fault in a single-phase transformer (working as a stand alone unit). I have the following observation but don't know the reason behind it:-

    The fundamental component in the no-load current is increasing under fault, but all other harmonics (3rd, 5th. 7th etc) remain almost unchanged. So, under fault the Total Harmonic Distortion (THD) of the no-load current is improving i.e. decreasing.

    Higher is the level of fault (i.e. number of turns shorted), lower is the no-load current THD.

    Any ideas, why this trend is happening ?

    Cheers,
    Shanto
     
  2. jcsd
  3. Aug 14, 2013 #2

    jim hardy

    User Avatar
    Science Advisor
    Gold Member
    2016 Award

    My guess:
    Leakage reactance at nth harmonic is nX its line frequency number of ohms. So harmonic currents see more ohms of series reactance than does fundamental current.

    What are properties of the iron core at harmonic frequencies?
    Try some searches on "complex permeability".
    Above some frequency well into audio range the iron no longer has any effective permeability .

    http://www.diva-portal.org/smash/get/diva2:125733/FULLTEXT01.pdf [Broken]

    So as frequency goes up, leakage reactance becomes increasingly larger proportion of total because the core acts less and less like textbook iron..

    That can't be the whole answer, but hopefully is food for thought.
     
    Last edited by a moderator: May 6, 2017
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Detection of inter-turn winding-short fault in 1-phase transformer
  1. Phase to Phase fault? (Replies: 1)

Loading...