4-2. A 13.8-kV, 50-MVA, 0.9-power-factor-lagging, 60-Hz, four-pole Y-connected synchronous...

4-2. A 13.8-kV, 50-MVA, 0.9-power-factor-lagging, 60-Hz, four-pole Y-connected synchronous generator has a synchronous reactance of 2.5 and an armature resistance of 0.2 At 60 Hz, its friction and windage losses are 1 MW, and its core losses are 1.5 MW. The field circuit has a dc voltage of 120 V, and the maximum IF is 10 A. The current of the field circuit is adjustable over the range from 0 to 10 A. The OCC of this generator is shown in Figure P4-1.

(a) How much field current is required to make the terminal voltage VT (or line voltage VL ) equal to 13.8 kV when the generator is running at no load?

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

(c) What is the phase voltage of this generator at rated conditions?

(d) How much field current is required to make the terminal voltage VT equal to 13.8 kV when the generator is running at rated conditions?

(e) Suppose that this generator is running at rated conditions, and then the load is removed without changing the field current. What would the terminal voltage of the generator be?

(f) How much steady-state power and torque must the generator's prime mover be capable of supplying to handle the rated conditions?

(g) Construct a capability curve for this generator.