9.4. The one-line diagram of a simple three-bus power system is shown in Figure 9.21 Each generator is represented by an emf behind the subtransient reac- tance. All impedances are expressed in per unit on a common MVA base. All resistances and shunt capacitances are neglected. The generators are operat- ing on no load at their rated voltage with their emfs in phase. A three-phase fault occurs at bus 3 through a fault impedance of Zy=j0.19 per unit. (a) Using Thévenin's theorem obtain the impedance to the point of fault and the fault current in per unit. (b) Determine the bus voltages and line currents during fault. j0.05 j0.30 j0.075 j0.75 1 2. j0.45 3 FIGURE 9.21 One line diagram for Problem 9 4