1. Not finding help here? Sign up for a free 30min 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!

The operation of magnetically coupled circuits

  1. Sep 14, 2013 #1
    1. The problem statement, all variables and given/known data

    A transformer has 600 primary turns and 150 secondary turns. The primary and the second resistances are 0.25Ω and 0.01 Ω respectively and the corresponding reactances are 1.0Ω and 0.04Ω respectively.
    Detemine the equivalent:
    1. resistance
    2. the reactance and
    3. the equivalent impedance reffered to the primary winding
    4. the phase angle of the impedance.

    Anyone could help me with this question? Thank you

    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Sep 14, 2013 #2
    I have been trying to answer some of them myself.
    For equivalent resistance:
    2
    Re= R1 + R2= R1 + R2 ( V1 : V2)

    Re= 0.41Ω

    For equivalent reactance:
    2
    Xe= X1 + X2' = X1 + X2 ( V1: V2)

    Xe= 1.64 Ω

    Am i correct?
     
  4. Sep 14, 2013 #3

    rude man

    User Avatar
    Homework Helper
    Gold Member

    Is there a load on the secondary? If not, just ignore the secondary winding altogether and solve the circuit with the primary winding only.
     
  5. Sep 14, 2013 #4
    Thanks. I will solve it OK now
     
  6. Sep 14, 2013 #5

    gneill

    User Avatar

    Staff: Mentor

    The problem may be referring to the transformer equivalent model referred to the primary. If so, the results reported by Agata78 in post #2 look correct (although the math as presented is not correct as the turns ratio should be squared in both cases).
     
  7. Sep 14, 2013 #6

    rude man

    User Avatar
    Homework Helper
    Gold Member

    If there is no load there is no secondary circuit. There is only a single inductor. The model, turns ratio, secondary leakage inductance and resistance do not matter.
     
  8. Sep 14, 2013 #7

    gneill

    User Avatar

    Staff: Mentor

    The problem may be referring to the model alone and not a complete circuit. Or, if you like, consider the secondary to be shorted. The OP would have to put the problem in context to clarify (is the problem associated with a chapter covering the transformer model, for example). Otherwise it's hard to see the point of providing the all the information that's given.
     
  9. Sep 14, 2013 #8

    rude man

    User Avatar
    Homework Helper
    Gold Member

    You can't short the secondary without toxic smoke! This is a power xfmr; look at the primary and secondary winding impedances. The components in the model referring to the secondary winding may be totally removed without affecting the four things asked for in the problem if there is no load.

    My suspicion is that either the OP left out load characteristics, or it's a trick question. Probably the former.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: The operation of magnetically coupled circuits
  1. Coupled circuits (Replies: 7)

Loading...