3-ph fault - LV bus - Two transformers - considering source impedance

       Consider a S/S having two transformers of (a) 132/33kV 25 MVA having leakage reactance of  ??.? %  and (b) 132/33kV 50 MVA having leakage reactance of  ??.? %  . For this substation 132kV bus 3-phase fault level is  ????  MVA. Find out the 3-phase 33kV Bus fault current.

(Note: Consider Base MVA as 100).

1) Using reverse engineering and formula Fault MVA = BaseMVAx100/X1s; Source +ve seq % impedance (XS) with base MVA 100 =    %

2a) 25 MVA % impedance (XT1) with base MVA 100    %

2b) 50 MVA % impedance (XT2) with base MVA 100    %

3) Equivalent % impedance between source and fault point will be                                      X1S + (XT1 || XT2) =  

4) 33kV Bus 3-Ph fault MVA =     MVA.

5) 33kV Bus 3-Ph fault Current =     Amp.

Topic FLTCALC Ex-3 Your score is:

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ABD1 ABD2 JALN PRBN NND1 NND2 LTR1 LTR2 BEED PRLI EKTN GRWL WALJ TPTN KMBH