A 1100-kVA, 4600-V, 60-Hz, three-phase, four-pole synchronous motor is to be driven from a variable-frequency, three-phase, constant V/Hz inverter rated at 1250-kVA. The synchronous motor has a synchronous reactance of 1.18 per unit and achieves rated open-circuit voltage at a field current of 85 A.

a. Calculate the rated speed of the motor in r/min.

b. Calculate the rated current of the motor.

c. With the motor operating at rated voltage and speed and an input power of 1000-kW, calculate the field current required to achieve unity-power factor operation. The load power of part (c) varies as the speed to the 2.5 power. With the motor field-current held fixed, the inverter frequency is reduced such that the motor is operating at a speed of 1300 r/min.

d. Calculate the inverter frequency and the motor input power and power factor.

e. Calculate the field current required to return the motor to unity power factor.