The nameplate on a 25-MVA, 60-Hz single-phase transformer indicates that it has a voltage rating of 8.0-kV:78-kV. A short-circuit test from the high-voltage side (low-voltage winding short circuited) gives readings of 4.53 kV, 321 A, and 77.5 kW. An open-circuit test is conducted from the low-voltage side and the corresponding instrument readings are 8.0 kV, 39.6 A, and 86.2 kW.
a. Calculate the equivalent series impedance of the transformer as referred to the high-voltage terminals.
b. Calculate the equivalent series impedance of the transformer as referred to the low-voltage terminals
c. Making appropriate approximations, draw a T equivalent circuit for the transformer.