Originally posted by: assenay
I am not sure if I understand your question but let me give you ask you, did u understand the difference between Symetrical component and 3-phase system if No then try to understand the difference between them and that will clear your doubt
Hi thanks for the reply. Yes I understand symmetrical component however it still doesn't explain the problem.
Sorry perhaps my initial question isn't very clear. Here's a better example.
Q) An electricity supply system developes an earth fault at a feeder cable connected to a 6.6KV busbar. The apparent power at the fault point is 26.1MVA.
Determine the current at the fault point.
Now to do this I believe you would use: Fault current = (Fault MVA) / (root 3 x V Line). Substituting in the number this would be: 26.1(x10^6) / [(root 3) x 6.6(x10^3)] = 2283 Amps.
The part I'm getting confused at is, if 6.6KV is the Line Voltage at the feeder cables why would you multiply the line voltage by root 3 when it is not a phase voltage?