A 25 kVA, 400 V, 3-phase synchronous generator delivers rated kVA at rated voltage at 0.8 pf lagging. The per phase (star basis) armature resistance and synchronous reactance respectively are 0.66 Ω and 7.1 Ω. The field winding is supplied 10.6 A at 110 V. The friction and winding loss is estimated to be 480 Ω and iron loss as 580 Ω. Calculate:
(a) the full-load efficiency.
(b) the terminal voltage when the load is thrown off.