A 20-MVA three-phase Y-connected 13,800-V two-pole 60-Hz generator has an armature resistance of 0.12 2 per phase and a synchronous reactance of 3.6 Q2 per phase. Find the field excitation voltage at no load, half load, and full load for power factors of (a) 0.8 leading, (b) unity, and (c) 0.8 lagging with rated terminal voltage.