The nameplate on a 7.97-kV: 460-V, 75-kVA, single-phase transformer indicates that it has a series reactance of 12 percent (0.12 per unit).
a. Calculate the series reactance in ohms as referred to (i) the low-voltage terminal and (ii) the high-voltage terminal.
b. If three of these transformers are connected in a three-phase Y-Y connection, calculate (i) the three-phase voltage and power rating, (ii) the per unit impedance of the transformer bank, (iii) the series reactance in ohms as referred to the high-voltage terminal, and (iv) the series reactance in ohms as referred to the low-voltage terminal.
c. Repeat part (b) if the three transformers are connected in Y on their HV side and A on their low-voltage side.