QUESTION 4 A 6-bus power system network is shown in Figure 4 and sequence reactance for generators, transformers and lines are tabulated in Table Q4. Investigate the fault current of the following types of fault happens: i. A bolted single line to ground fault at bus 5 (13 marks) ii. A bolted double line to ground fault at bus 5 (4 marks) iii. A bolted line-to-line fault at bus 5 (3 marks) Evaluate the new line-to-line fault at bus 5, through a fault impedance Zf=;0.05 pu. Is the fault current increase or decreases from the value in (iii)? (5 marks) Device Gi G2 T T2 T3 T4 TL23 TL56 Table 24 Xi (pu) X2 (pu) 0.2 0.12 0.33 0.22 0.2 0.2 0.225 0.225 0.16 0.16 0.27 0.27 0.14 0.14 0.35 0.35 Xo (pu) 0.06 0.066 0.2 0.225 0.16 0.27 0.3 0.6 1 Ti 2 3 T2 4 Line 1 BE 500kV Y G T; 5 6 T4 Line 2 275kV XA Figure Q4 QUESTION 4 A 6-bus power system network is shown in Figure 4 and sequence reactance for generators, transformers and lines are tabulated in Table Q4. Investigate the fault current of the following types of fault happens: i. A bolted single line to ground fault at bus 5 (13 marks) ii. A bolted double line to ground fault at bus 5 (4 marks) iii. A bolted line-to-line fault at bus 5 (3 marks) Evaluate the new line-to-line fault at bus 5, through a fault impedance Zf=;0.05 pu. Is the fault current increase or decreases from the value in (iii)? (5 marks) Device Gi G2 T T2 T3 T4 TL23 TL56 Table 24 Xi (pu) X2 (pu) 0.2 0.12 0.33 0.22 0.2 0.2 0.225 0.225 0.16 0.16 0.27 0.27 0.14 0.14 0.35 0.35 Xo (pu) 0.06 0.066 0.2 0.225 0.16 0.27 0.3 0.6 1 Ti 2 3 T2 4 Line 1 BE 500kV Y G T; 5 6 T4 Line 2 275kV XA Figure Q4