A 20-kVA 20,000/480-V 60-Hz distribution transformer is tested with the following results: Open-circuit test Short-circuit test (measured from secondary side) Voc=480 V (measured from primary side) Vsc=1130 V 1sc = 1.00 A Psc = 260 W loc=1.51 A Voc=271 W (a) Find the per-unit equivalent circuit for this transformer at 60 Hz. (b) What would the rating of this transformer be if it were operated on a 50-Hz power system? (c) Sketch the equivalent circuit of this transformer referred to the primary side if it is operating at 50 Hz.