The nameplate on a 50-MVA, 60-Hz single-phase transformer indicates that it has a voltage rating of 8.0-kV: 78-kV. An open-circuit test is conducted from the low-voltage side, and the corresponding instrument readings are 8.0kV, 62.1A, and 206kW. Similarly, a short-circuit test from the low-voltage side gives readings of 674 V, 6.25 kA, and 187 kW.
a. Calculate the equivalent series impedance, resistance, and reactance of the transformer as referred to the low-voltage terminals.
b. Calculate the equivalent series impedance of the transformer as referred to the high-voltage terminals.
c. Making appropriate approximations draw a T equivalent circuit for the transformer.
d. Determine the efficiency and voltage regulation if the transformer is operating at the rated voltage and load (unity power factor).