Question

A three phase, salient pole synchronous motor is connected to an infinite bus. It is operated at no load at normal excitation. The field excitation of the motor is first reduced to zero and then increased in the reverse direction gradually. Then the armature current
1. increases continuously
2. first increases and then decreases steeply
3. first decreases and then increases steeply
4. remains constant

Answer 1

Correct Answer - Option 2 : first increases and then decreases steeply

A 3-phase synchronous motor, connected to infinite bus, is operating at no load at normal excitation. The field excitation of the motor is first decreased to zero and then increased in the reverse direction. The armature current of the synchronous motor will increase first and then decrease.