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3 phase xfmr fault calculation

3 phase xfmr fault calculation

3 phase xfmr fault calculation

(OP)
help...I can't remember the calaculation for fault current at the secondary of a 3 phase transformer.

RE: 3 phase xfmr fault calculation

Try the following simplified short cut method:

    Isc = Ifl/Zt

   Were:
    Ifl=KVAtransf/1.73xKV  (Transf full load current)
    Zt = Z%/100 (Transformer impedance)

Be ware that this method consider an infinte source on the primary side and do not include motor short circuit contribution from the secondary side.

If you should be interested in more detail calc. consuly the IEEE Std 141 and 142.

RE: 3 phase xfmr fault calculation

Suggestion: Reference:
1. ANSI/IEEE Std 242-2001 Buff Book

RE: 3 phase xfmr fault calculation


Administrative aside: There’s that upstart IEEE Draft Std P551 Calculating AC Short-Circuit Currents in Industrial and Commercial Power Systems  An excerpt of the text is: standards.ieee.org/colorbooks/sampler/VioletBook.pdf
  

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