Consider a bank of three single-phase two-winding transformers whose high-voltage terminals are connected to a three-phase, $13.8-\mathrm{kV}$ feeder. The low-voltage terminals are connected to a three-phase substation load rated 2.1 MVA and $2.3 \mathrm{kV}$. Determine the required voltage, current, and MVA ratings of both windings of each transformer, when the high-voltage/low-voltage windings are connected (a) $\mathrm{Y}-\Delta$, (b) $\Delta-\mathrm{Y}$, (c) $\mathrm{Y}-\mathrm{Y}$, and (d) $\Delta-\Delta$.