A 5000-KVA 230/13.8-kV single-phase power transformer has a per-unit resistance of 1 percent and a per-unit reactance of 5 percent (data taken from the transformer's nameplate). The open-circuit test performed on the low-voltage side of the transformer yielded the following data: Voc = 13.8 kV loc = 15.1 A Poc = 44.9 kW (a) Find the equivalent circuit referred to the low-voltage side of this transformer. (b) If the voltage on the secondary side is 13.8 kV and the power supplied is 4000 kW at 0.8 PF lagging, find the voltage regulation of the transformer. Find its efficiency.