Pretty much wrapped up the NCEES power practice problems except for number 530. Might be a simple solution but I can't see it in their solution. Also having a hard time picturing this problem as well. It calls for a 1,000kVA, 12.47kV-480Y/277V transformer with 4% impedance which feeds a 480V bus. The fault duty of the 12.47kV system is 40MVA. Assuming the transformer and the 12.47kV system have the same X/R ratio, you are asked to find the 3-phase short circuit current at the 480V bus. In their solution I am not sure how they got the 0.025pu impedance when calculating the short circuit current.
Any info would be appreciated.
Thanks a bunch.
Good luck to all.
lease:
Any info would be appreciated.
Thanks a bunch.
Good luck to all.
lease: