A Y-connected synchronous generator rated 20 MVA at 13.8

Chapter , Problem 8.34

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A Y-connected synchronous generator rated 20 MVA at 13.8 kV has a positivesequence reactance of j2.38 W, negative-sequence reactance of j3.33 W, and zero-sequence reactance of j0.95 W. The generator neutral is solidly grounded. With the generator operating unloaded at rated voltage, a so- called single line-to-ground fault occurs at the machine terminals. During this fault, the line-to-ground voltages at the generator terminals are Vag _ 0, Vbg _ 8:071 ?102:25 , and Vcg _ 8:071 102:25 kV. Determine the sequence components of the generator fault currents and the generator fault currents. Draw a phasor diagram of the pre-fault and post-fault generator terminal voltages. (Note: For this fault, the sequence components of the generator fault currents are all equal to each other.)