A two-winding transformer rated at 9-kVA, 120/90-V, 60-HZ has a core loss of 200 W and a full-load copper loss of 500 W.
(a) The above transformer is to be connected as an auto transformer to supply a load at 120 V from 210 V source. What kVA load can be supplied without exceeding the current rating of the windings? (For this part assume an ideal transformer.)
(b) Find the efficiency with the kVA loading of part (a) and 0.8 power factor.