Discuss the problem posed in Prob. 8.5 by using the circuit model of the motor.
Prob. 8.5:
A synchronous motor is drawing power from a large system (assumed infinite) with its field current adjusted so that the armature current has unity power factor. Assume the armature resistance and leakage reactance to be negligible.
With the load torque remaining constant, the field current of the motor is raised by 10%.
Discuss by means of mmf phasor diagrams the changes that occur in the power output, magnitude and phase angle of the armature current and torque angle.
If, instead of the field current, the load torque is increased by 10%, what changes will occur?