UNSYMMETRICAL FAULT CALCULATIONS – PART – 19 - SINGLE LINE TO GROUND FAULT – TWO PROBLEMS

PROBLEM – 01

A star point of a 3 kV, 3 MVA three phase synchronous generator is solidly grounded. It's positive, negative and zero sequence impedances are 2.4, 0.45 and 0.3 ohms. The generator operating unloaded sustains a resistive fault between the R phase and ground. This fault has a resistance of 1.2 ohms. Calculate the fault current and the voltage to ground of the R phase.

PROBLEM – 02

A three phase 30 MVA, 33 kV alternator having X1 = 0.18 pu and X2 = 0.12 pu and X0 = 0.10 pu, based on its rating, is connected to a 33 kV overhead line having X1 = 6.3 ohms and X2 = 6.3 ohms and X0 = 12.5 ohms per phase. A single line to ground fault occurs at the remote end of the line. The alternator neutral is solidly grounded. Calculate the fault current.