A 20 kVA, 1000 V/200 V, 50 Hz single-phase transformer gave the following test results:- Open Circuit Test: 200 V, 3.5 A, 400 W on L.V. side Measurement Short Circuit Test: 50 V, 30 A, 1200 W on H. V. side Measurement Evaluate (a) the core loss resistance and magnetizing reactance referred to the H.V. side; (5 marks) (b) the equivalent winding resistance and reactance referred to the H.V. side; (5 marks) (c) the loading at which maximum efficiency is attained; (5 marks) (d) the value of the maximum efficiency at unity power factor. (5 marks)