I already know the answer but why at the zero sequence there is .21 pu impedance near G3
Neglect-Y transformer phase shifts
9.6 Faults at bus n in Problem 9.5 are of interest (the instructor
selects m=1, 2, 3, or 4. Determine the Thevenin equivalent of each
sequence network as viewed from the fault bus. Prefault voltage is 1.0 per unit. Prefault load currents and -Y phase shifts are neglected.