Power Factor

Discussion in 'Homework Help' started by goose12, Sep 16, 2014.

  1. goose12

    Thread Starter New Member

    Apr 8, 2013
    A load of 10 kW at a PF of 0.7 lag is supplied at 230 V from a feeder whose impedance
    is 0.1+j0.4Ω. Find the sending-in voltage and the PF. (Partial answer: PF = 0.66 lag).
    What I know:
    P = 10 kW
    |S| = 10/ pf = 14.29 kVA
    Q = sqrt(S^2 - P^2) = 10.208 kVAR

    I calculated the load current using the equation P = VI*pf = 62.11 A (but don't know how to get phase angle) Now I have the load voltage and current (w/o phase angle), and now I am stuck. I don't see how the two power factors will relate at all to be honest.
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    For convenience assume the load voltage has reference 0 phase angle. That is the load voltage is 230V at phase 0 deg.
    The load current phase is then -acos(0.7).
    Does that help?