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Homework Help: Voltage, real reactive power question

  1. Apr 27, 2012 #1
    1. The problem statement, all variables and given/known data

    A 33 kV single phase generator is supplying a customer a load through a cable with an impedance j2 ohms

    a.What voltage would the customer experience if rated current of 500 A is drawn at power factor of unity at the customer end?

    b. How much active and reactive power would be provided by the generator?

    2. Relevant equations
    V = IZ
    P = IV

    PF = P/S = IV cos phi

    3. The attempt at a solution

    Part a: Do I need to find the total impedance using V = IZ equation, and then calculate the impedance of the customer load by subtraction, and then sub this impedance of the load back into the V = IZ formula to find the customer voltage?

    Or is the customer voltage simply 33 kV?

    I am very confused by terminology?

    Any help much appreciated
  2. jcsd
  3. Apr 27, 2012 #2
    Are you trying to solve this using RMS Values ?
  4. Apr 27, 2012 #3
    we have been told to assume that all voltage values given are rms voltage values so we don't need to worry about that...
  5. Apr 27, 2012 #4
    Would it be possible to just say that P = S and hence the voltage at the customer end will also be 33kV?
  6. Apr 28, 2012 #5
    You have a circuit with three elements, a voltage source of 33kV, an impedance of j2 ohms, and another impedance which is assumed to be purely resistive. That is, the generator supplies 33kV to some network, what the customer sees, you don't know.

    Equivalent Z is Z=R+2j, that is 33kV = (R+2j)*500A, which yields the load impedance. The voltage drop is then 33kV*R/(R+2j).

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