1. Can somebody please explain why the 3-phase short circuit current calculation is:
\(I_{SC}\)=\(I_{FL}\))/\(Z_{p.u.}\)
I can't make any sense of this, and the only way it does make sense to me is if I assume that in the symmetrical component analysis, the voltage in the postivie sequence is equal to 1.0 p.u., but I don't think that is always the case so I'm not comfortable with the above generalization (unless I'm missing something). Here's my reasoning for the above:
\(I_{a(p.u.)}\)=\(I_{pos.seq(p.u.)}\)=\(V_{p.u.}\)/\(Z_{p.u.}\)
\(I_{SC}\)=\(I_{p.u.}\)*\(I_{FL}\)
\(I_{SC}\)=(\(V_{p.u.}\)*\(I_{FL}\))/\(Z_{p.u.}\)
2. During a single phase to ground fault, why do we say that the currents in phase B and C are 0? I can't understand why that would be the case, if only one phase is grounded. If the system is connected to a load, and one phase is grounded, the other two phases are still complete circuits, so why won't there be current?
Thanks in advance....I can't find answers to these questions anywhere.
\(I_{SC}\)=\(I_{FL}\))/\(Z_{p.u.}\)
I can't make any sense of this, and the only way it does make sense to me is if I assume that in the symmetrical component analysis, the voltage in the postivie sequence is equal to 1.0 p.u., but I don't think that is always the case so I'm not comfortable with the above generalization (unless I'm missing something). Here's my reasoning for the above:
\(I_{a(p.u.)}\)=\(I_{pos.seq(p.u.)}\)=\(V_{p.u.}\)/\(Z_{p.u.}\)
\(I_{SC}\)=\(I_{p.u.}\)*\(I_{FL}\)
\(I_{SC}\)=(\(V_{p.u.}\)*\(I_{FL}\))/\(Z_{p.u.}\)
2. During a single phase to ground fault, why do we say that the currents in phase B and C are 0? I can't understand why that would be the case, if only one phase is grounded. If the system is connected to a load, and one phase is grounded, the other two phases are still complete circuits, so why won't there be current?
Thanks in advance....I can't find answers to these questions anywhere.