Question

A
Synchronous generator SOMVA, 13.8 kV has Sub- transcient Reactance.
b) negative Sequence reactance and zero Sequence Reactance equal to
jol, jo.I and jooa Respectively. If a cig
a CLG fault occurs at the
terminal of the
generator neutral solidly grounded) find fault corrent​

Answer 1

Answer:

A 30 MVA, 3-phase, 50 Hz, 13.8 kV, star-connected synchronous generator has positive, negative and zero sequence reactances, 15%, 15% and 5% respectively. A reactance (Xn) is connected between the neutral of the generator and ground. A double line to ground fault takes place involving phases ‘b’ and ‘c’, with a fault impedance of j0.1 p.u. The value of Xn (in p.u.) that will limit the positive sequence generator current to 4270 A is _________.

Answer : 1.05 : 1.15