A 100 kVA, 11 kV/231 V transformer has HV and LV winding resistances of 8.51 Ω and 0.0038 Ω respectively. It gave the following test results:
Calculate
(a) Equivalent leakage reactance of the transformer
(b) Full load copper loss
(c) Efficiency at full-load and half full-load at 0.85 lagging power factor