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Homework Help: Transformer Primary and secondary currents

  1. Jan 6, 2012 #1
    1. The problem statement, all variables and given/known data

    A single phase transformer has the following rating : 120kVA. 2000v/100v, 60 Hz with
    1000 primary turns.


    a.Secondary turns
    b.The rated primary and secondary currents

    2. Relevant equations

    Vp/Vs = Np/Ns

    3. The attempt at a solution

    a. I have used the Vp/Vs = Np/Ns to work out secondary turns
    1000 x 100/2000 which gave me 50 secondary turns.

    b. I arent sure if I have gone about this the right way and just wanted to check.

    I divided the 120000VA by the primary voltage of 2000 to give me 60A. Is this correct to do this.
    Then with my 60A I put that into the Vp/Vs = Ip/Is which gave me 3A as secondary current.

    Could someone please tell me if this is correct thanks
  2. jcsd
  3. Jan 6, 2012 #2
    Vp/Vs = Ip/Is is not the correct equation.... have another look at it.
    If the transformer is 100% efficient then power supplied = power delivered.
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