From figure below, if 3 phase bolted fault occurs. Using Zbus method to choose a suitable rating of C.B’s. Data are as follows: GI: 100 MVA, 22 Kv,Xgı" = 0.2 pu G2: 100 MVA, 22 KV, X2¯=0.15 pu TRI: 100 MVA, 22/220 KV, XTR1 =0.1 pu TR2: 100 MVA, 22/220 KV, XTR2 =0.1 pu CB TR1 2 ZTL-J50 ohm TR2 св св 3 Zload =(0.2 + j0.1) pu CB

Q.3 When a line-to-ground fault occurs, the current in faulted phase 'a' is 100A. The zero-sequence current in phase 'c' is r

Please solve Q1(C) ONLY. Q1(A) is for reference.

The subject is: Smart Grid Applications and Technologies

3.8. Three identical 9-MVA, 7.2-kV/4.16-kV, single-phase transformers are con- nected in wye on the high-voltage side and delta on the low voltage side. The equivalent series impedance of each transformer referred to the high-voltage side is 0.12 + j0.82 S per phase. The transformer supplies a balanced three- phase load of 18 MVA, 0.8 power factor lagging at 4.16 kV. Determine the line-to-line voltage at the high-voltage terminals of the transformer.

(b) A 30000 kVA, 13.8 kV generator with X = 18% is connected to a bus which supplies two identical motors as shown in the Figure 2. The subtransient reactance X of each motor is 25% on a base of 6000 kVA, 7 kV. The bus voltage at the motors is 7 kV when a three phase fault occurs at the point P. For the fault specified, determine (a) the subtransient current in the fault (b) the subtransient current in breaker A and (c) the symmetrical short circuit interrupting current in the fault and in breaker A. юю DO A P 0-0 Gen. Figure 2 Motors