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2. Consider a 20-kVA, 230/2300-V, 50 Hz single-phase transformer. Open-circuit and short-circuit tests on the transformer gave the following results: Open-circuit test, with the high-voltage side opened: Vo = 230 V, Loc=0.75 A, Poc = 100 W Short-circuit test, with the low-voltage side short circuited: Vse = 50 V, Ise - 8.7 A, Pse = 125 W (a) Determine the approximate equivalent circuit referred to the high-voltage side. (8 Marks) (b) Using the equivalent circuit obtained in part (a), determine the secondary terminal voltage when the input voltage is 230 V and the transformer is delivering rated load current at 0.85 power factor lagging. (Hint: Use the secondary terminal voltage as the reference, i.e., V240° and the input voltage as 23020, to solve for 0, and V2.) (10 Marks) (c) Using the data given in part (a) or otherwise, find the efficiency of the transformer at 80% of full load and 0.85 power factor lagging, with the secondary terminal voltage maintained at 2300 V. (7 Marks)