A synchronous motor is running with normal excitation. When the load is increased, the armature current drawn by it increases because
Correct answer: D. Er (net resultant voltage) in armature is increased
- A. speed of the motor is reduced
- B. power factor is decreased
- C. Eb (back e.m.f.) becomes less than V (applied voltage)
- D. Er (net resultant voltage) in armature is increased
- E. none of the above
Explanation
Increasing load increases the torque angle, which increases the resultant voltage across the synchronous impedance and hence the armature current. The speed remains essentially constant, so speed reduction is not the cause.
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