The system shown in Figure 9.28 except that the transformers are now \(\mathrm{Y}-\mathrm{Y}\) connected and solidly grounded on both sides.

(a) Determine the bus impedance matrix for each of the three sequence networks.

(b) Assume the system to be operating at nominal system voltage without prefault currents when a bolted single-line-toground fault occurs on phase A at bus 3. Compute the fault current, the current out of phase \(\mathrm{C}\) of machine 2 during the fault, and the line-toground voltages at the terminals of machine 2 during the fault.

1 T 2 Machine 1 10 Y Y (3) T 4 to Machine 2