Star Bridge Rectifier

Discussion in 'General Electronics Chat' started by haruna, Jun 7, 2014.

  1. haruna

    Thread Starter New Member

    Mar 23, 2013
    1
    0
    Hello all,
    I am designing a rectifier with a star configuration and I need help clarifying some aspects of the calculations; Screen shots of the circuit is attached.

    Power Out = 120 kW
    Voltage Out = 15V

    DC current = 120,000/15 = 8000amps
    Transformer rms current = 0.408 x 8000 = 3264amps
    Transformer Secondary L-L voltage = (15V + diode drop) x 1.28
    = (15 +1.5) x 1.28 = 21.12V rms
    Transformer secondary phase voltage = 12.19V rms


    Now the KVA = Sqrt(3) x Vsecondary x secondary current
    = sqrt(3) x 21.12 x 3264 = 119kVA

    I need clarification on the KVA, which seems lower than the total DC power of the unit.

    Thanks
     
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