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Apparent power, impedance and alternating current.

  1. Apr 21, 2013 #1
    1. The problem statement, all variables and given/known data
    Two serially connected impedances one with [itex]\Phi[/itex] = π/3 and other with [itex]\Phi[/itex] = 0. They have apparent power of S1=S2=200VA. Find total apparent power.

    2. Relevant equations

    S = sqrt(P^2 + Q^2)

    3. The attempt at a solution

    so cosPhi = P1/S1. So P1=cosπ/3*200=100W. For other one P2 = cos0*200=200W. How should I continue? Should I find Q too and derive somehow a equation to sum those powers?
  2. jcsd
  3. Apr 21, 2013 #2
    The complex power, S, delivered to the load is:
    S = S1 + S2

    and the angle between S1 and S2 is the same as the angle between the impedances.

    You want to find the apparent power |S| = |S1 + S2|. If, say:
    S1 = 200∠0
    S2 = 200∠π/3

    Try drawing them in the complex plane. The length of their sum is the answer you're after.
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