Equipment ratings for the four-bus system shown in Figure 2 are as follows: Generator G1: 500 MVA, 13.8 kV, X" =0.20 pu. Generator G2: 750 MVA, 18 kV, X" =0.18

pu. Generator G3: 1000 MVA, 20 kV, X" = 0.17 pu. Three-phase Delta-Y transformer T1: 500 MVA, 13.8(A)/500(Y) kV, X= 0.12 pu. Three-phase Delta-Y transformer T2: 750 MVA, 18(A)/500(Y) kV, X = 0.10 pu. Three-phase Delta-Y transformer T3: 1000 MVA, 20(A)/500(Y) kV, X 0.10 pu. Each 500kV line: X1 = 50 Q. A three phase short circuit occurs at bus 1, where the prefault voltage is 525 kV. Prefault load current is neglected. Draw the positive-sequence reactance diagram in per unit on a 1000-MVA, 20-kV base in the zone of generator G3. Determine (a) the subtransient fault current in per unit and in kA RMS. (b)Contributions to the fault current from generator G1 and from line 1-2 in per unit. For both (a) and (b),perfault currents are neglected.