UNSYMMETRICAL FAULT CALCULATIONS – PART – 15 – SINGLE LINE TO GROUND FAULT – PROBLEM

PROBLEM

A 25 MVA, 11 kV three-phase generator has a direct sub-transient reactance of 0.25 pu, negative sequence reactance on 0.35 pu and zero sequence reactance of 0.1 pu. The neutral is grounded solidly grounded. Determine the fault current and the line to line voltages for sub-transient conditions when the single line to ground fault occurs on phase R. The generator operating unloaded at rated voltage.