Two synchronous motors having subtransient reactances of 0.8 and 0.25 p.u., respectively, on a base of 500 V 2 MVA are connected to a bus. This motor bus is connected by a line having a reactance of 25 mΩ to a bus of a power system. At the power system bus the short circuit MVA of the power system is 12.5 MVA for a nominal voltage of 500 V. A symmetrical bolted three phase fault occurs at the motor terminals when the voltage at the motor bus is 450 V.
a) Calculate the fault current. Neglect the load current.