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: Hi guys, i was studying on transformers losses, i need help in some

  1. Oct 18, 2011 #1
    hi guys, i was studying on transformers losses, i need help in some problems.

    why open-circuit test show only excitation losses and not i2R losses..

  2. jcsd
  3. Oct 18, 2011 #2
    Re: transformers

    What reference are you referring to that seems to ignore copper losses?
  4. Oct 18, 2011 #3

    jim hardy

    User Avatar
    Science Advisor
    Gold Member

    Re: transformers

    think about that for a moment

    what is magnitude of current in open circuit test?

    just magnetizing current 'cause there's no load on transformer.....
    which for a quality transformer should be small (though not zero)
    and when you express it as a fraction of rated current and square that it gets even smaller

    so if your text did not state that the magnetizing current is small enough to ignore then it was an error of omission by the author,

    and it is not always the case that magnetizing current is negligible...
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook