A 3 phase fault occurs at point F as shown in figure. Determine the critical clearing angle for the system. The generator is delivering 1.0 p.u power under prefault condition

A generator is connected through a transformer to a synchronous motor as shown in the following figure. (All values in this problem are per unit.) Before the fault V,=0.9,1=1 with power factor 0.8 lagging. jX, P + jX ds jX" dm + E. E The reactances are Xd=0.15 , X,=0.1 , X âm=0.35. A symmetric fault occurs at P. Find the per-unit current magnitudes in the fault, the generator and the motor (a) using subtransient voltages. (b) using a Thevenin equivalent.