Suppose the transformer in this power system is changed from a Y-Y to a Y-D, with the Y-connection solidly grounded. Nothing else changes in the power system. Now suppose that a single-line-to-ground fault occurs on the 138 kV transmission line near to the point where it is connected to the transformer.
(a) How much current flows at the point of the fault during the subtransient period?
(b) What is the voltage at the terminals of the generator during the subtransient period?
(c) How much current flows at the point of the fault during the transient period?
(d) What is the voltage at the terminals of the generator during the transient period?