Coordinate the relays for maximum fault currents

Discussion in 'Homework Help' started by Jess_88, Feb 19, 2013.

  1. Jess_88

    Thread Starter Member

    Apr 29, 2011
    174
    1
    Hey guys,

    Going though a problem in my book, and I'm stuck on the max fault level used in the solution.
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    I can get the full load currents at each bus:
    I,fl3=100.41A
    I,fl2=167.35A
    I.fl1=351.43A
    Current Tap Settings
    Is,3=2.51A--->use 3A
    Is,2=4.18A--->use 5A
    Is,1=4.39A--->use 5A

    This is where I'm confused,
    TDS=>ratio3 = If/[I,pickup]
    In the solutions, the Max fault current (If) at B3 is 2000A...
    Shouldn't it be 1000A?

    Thanks guys :)
     
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