Three 100-MVA single-phase transformers, rated at 13.8 kV: 66.4kV, are to be connected in a three-phase bank. Each transformer has a series impedance of 0.0045 + j0.19 Ω referred to its 13.8-kV winding.

a. If the transformers are connected Y-Y, calculate (i) the voltage and power rating of the three-phase connection, (ii) the equivalent impedance as referred to its low-voltage terminals, and (iii) the equivalent impedance as referred to its high-voltage terminals.

b. Repeat part (a) if the transformer is connected Y on its low-voltage side and A on its high-voltage side.