Question-

A single-phase transformer is rated 100kVA, 2200:440 volts. When carrying rated current with the low voltage terminals short-circuited, the input power was 1.14kW, and the applied voltage 93V rms.

1) Determine the equivalent winding resistance and leakage reactance of the transformer referred to the low voltage side.

2) The primary voltage is adjusted so that the secondary voltage is 440V when the transformer is supplying rated load at a power factor of 0.8 leading. Calculate the primary terminal voltage and the percentage regulation.

3) The transformer consumes 700W under no-load conditions at rated voltage. Determine the value of load current for which the efficiency is maximum, and evaluate this efficiency at a power factor 0.7 lagging.