A 3 phase, 4 pole 1 MVA, power alternator has a synchronous impedance of (0.5+j5.5)O per phase. The alternator is to be synchronised with the ships bus bars operating at 50Hz, 6.6 kV (Line) and is to deliver 700kW and 550kVAr lagging to the system. Negelecting the winding resistance calculate:
(a) The generated e.m.f required to supply the load and load angle (rotor displacement) in both electrical and mechanical degrees
(b) The synchronising power in watts per degree
(c) If the excitation is increased by 20% and the load remains constant determine the new kVA and power factor
(d) The torque to force the machine to break from synchronism if the excitation is reduced that the generated e.m.f is 4kV (phase)