Need help with 3 phase q

Discussion in 'Homework Help' started by trx, Sep 27, 2009.

  1. trx

    Thread Starter New Member

    Sep 27, 2009

    Can anyone pleae help me with this questione.. How do I fine the impedance of the circuit ???

    A factory draws a total of 415kVA from a 2.4kV (line voltage) 3-phase supply. If the plant
    power factor is 0.875, calculate:
    a. The impedance of the plant per phase
    b. The phase angle between the line-to-neutral voltage and the line current​
    c. Draw a phasor diagram showing the voltages and currents of the three phases
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    There are a few approaches but I normally take this one

    * Calculate the VA load per phase - Q
    * Calculate the line-to-neutral voltage - Vln
    * Calculate I line = Q/Vln
    * Impedance per phase Zph = Vln/I line
    * Calculate current phase angle (θ) with respect to Vln where θ=acos(pf) and assume it is lagging pf
    * Draw your phasor diagram remembering that in a balanced 3-phase system the line currents and their phase angles will be equally balanced.