A 50-kVA 20,000/480-V 60-Hz single-phase distribution transformer is tested with the following results:
(a) Find the per-unit equivalent circuit for this transformer at 60 Hz.
(b) What is the efficiency of the transformer at rated conditions and unity power factor? What is the voltage regulation at those conditions?
(c) What would the ratings of this transformer be if it were operated on a 50-Hz power system?
(d) Sketch the equivalent circuit of this transformer referred to the primary side if it is operating at 50 Hz.
(e) What is the efficiency of the transformer at rated conditions on a 50 Hz power system, with unity power factor? What is the voltage regulation at those conditions?
(f) How does the efficiency of a transformer at rated conditions and 60 Hz compare to the same physical device running a 50 Hz?