1. A Y-connected, three-phase, 12 kV line-to-line voltage, 15 MVA, 50 Hz synchronous generator has reactance 20 per phase and negligible armature resistance. The generator supplies power to an infinite bus bar and generates 95% full load current at 0.9 lagging power factor.

a) Calculate the magnitude of the excited line-to-neutral emf.

b) Draw the phasor diagram for 1(a).

c) If the excited emf magnitude is increased 10% and the output real power is changed to 20 MW, determine the new armature current and the new power factor.

d) From your answer in (a), calculate the maximum three-phase real power that the generator can deliver before losing its synchronism.

e) What happens if the power angle is more than 90o?