Q. Three single-phase, 10-kVA, 2400/120-V, 60- Hz transformers are connected to form a three- phase, 4160/208-V transformer bank. Each of the single-phase transformers has an equivalent series impedance of 10 + j25  referred to the high-voltage side. The transformer bank is said to deliver 27 kW at 208 V and 0.9 power factor leading.

(a) Draw a schematic diagram of transformer connections, and develop a per-phase equivalent circuit.

(b) Determine the primary current, primary voltage, and power factor.

(c) Compute the voltage regulation.