4. A three-phase short circuit occurs at the generator bus (Bus 1) for the system shown in Figure 3. Neglecting prefault currents and assuming that that generator is operating at its rated voltage, determine the subtransient fault current using superposition. bus 1 bus 2 j65 0 G mm UW A 25 MVA 25 MVA 25 MVA 15 MVA 13.8 kV 13.2/69 kV 69/13.2 kV 13 kV 15% 11% 11% 15% Figure 3: One-Line Diagram Q4