NCEES # 513

[power62]

Using MVA method and impedence method (Z) I am getting fault current value of about 450 (close to answer B 455A) rather than correct answer of (A) 415. Any help/suggetions will be appreciated.

 

[knight1fox3]

Try this:

/>http://engineerboards.com/index.php?showtopic=20060

 

[Wael]

When using the MVA meathod remeber MVA for the line = KV*2/ IZI

dont include the angle of -90 in your calculations just the magnitude. therefore 100 MVA in parallel with 9.4 = 8.6 MVA

I= 8.6M/ 12K*1.731 = 413.13

 

[power62]

Thanks Wael.

I had right MVA value for the cable (transmission line). My transformer MVA value was off by factor of 10. Put in wrong info into calculator (two times) :beat: .

Now I am getting the right answer.