5-2. A 480-V 200-kVA 0.8-power-factor-lagging 60-Hz two-pole Y-connected synchronous gener...

5-2. A 480-V 200-kVA 0.8-power-factor-lagging 60-Hz two-pole Y-connected synchronous generator has a synchronous reactance of 0.25 Ω and an armature resistance of 0.03 Ω. At 60 Hz, its friction and windage losses are 6 kW, and its core losses are 4 kW. The field circuit has a dc voltage of 200 V, and the maximum I_F is 10 A. The resistance of the field circuit is adjustable over the range from 20 to 200 Ω. The OCC of this generator is shown in Figure P5-1.

(a) How much field current is required to make V_T equal to 480 V when the generator is running at no load?

(b) What is the internal generated voltage of this machine at rated conditions?

(c) How much field current is required to make V_T equal to 480 V when the generator is running at rated conditions?

(d) How much power and torque must the generator’s prime mover be capable of supplying?