fault current calc

Status
Not open for further replies.
E

Econsultant

Member
I recently received a response to a inquiry from a power co. source that implied a short circuit current at the flagside of a 500kva xfmr to be 34,000A,
My question is what side of the xfmr is the flag side. Line or load? Also does anybody have a handle on a free fault current calc program other than lotus 123? Excell maybe?
 
Econsultant said:
I recently received a response to a inquiry from a power co. source that implied a short circuit current at the flagside of a 500kva xfmr to be 34,000A,
My question is what side of the xfmr is the flag side. Line or load? Also does anybody have a handle on a free fault current calc program other than lotus 123? Excell maybe?
Click to expand...
Never heard that term but 34000 has got to be the secondary fault.
 
I've not heard that term before. Depending on the secondary voltage, it probably is not the fault current on the secondary side, as the infinite primary value calculated result for the secondary side isn't that high.
 
1500kva, 480v, 5.3%Z ==34,042A

2000kva, 480V, 7.1%Z == 33,882A

These numbers don't look out of line for a secondary fault current.

carl
 
The secondary lugs of a transformer (because of the way they stick out on the post in a rectangular fashion) are sometimes called the "flags". The "elbow side" and the "flag side", used instead of primary and secondary.
 
ron said:
I've not heard that term before. Depending on the secondary voltage, it probably is not the fault current on the secondary side, as the infinite primary value calculated result for the secondary side isn't that high.
Click to expand...
500 kva can come in 277/480 or 120/208. Assuming its 208 Transformer
500/(.208 x 1.73)= 1390/0.04 = 34750 amps.
I don't think its primary amps.
 
Status
Not open for further replies.
Top