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Homework Help: [Electrical Engineering] Three-phase transmission line problem

  1. Sep 26, 2012 #1
    1. The problem statement, all variables and given/known data

    A three-phase line delivers 3600 kW at its receiving end at a lagging power factor of 0.85. The line resistance and reactance are 5 Ohms and 8 Ohms per phase respectively. Given that the sending end line voltage is 33kV, you are asked to determine the receiving end line voltage.

    2. Relevant equations

    Z = R + jX
    z = 90 - arctan(X/R)

    p.f. = P/√(P²+Q²)

    P2 = Active power at the receiving end = 3600 kW
    Q2 = Reactive power at the receiving end = 2231.08 kVAR (found using the equation above)

    P2 = E1*E2*sin(z+d)/Z - (E2/Z)^2*R
    Q2 = E1*E2*cos(z+d)/Z - (E2/Z)^2*X

    3. The attempt at a solution

    I'm trying to solve this system of equations which has two unknows (d & E2) but I don't think that's the right approach... Any ideas?
  2. jcsd
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