In a synchronous motor, the magnitude of stator back e.m.f. Eb depends on___________?
Correct answer: B. d.c. excitation only
- A. load on the motor
- B. d.c. excitation only
- C. both the speed and rotor flux
- D. none of the above
Explanation
At constant supply frequency, synchronous speed is fixed, so the back e.m.f. is controlled by the rotor field flux, which is set by the d.c. excitation. In normal operation this makes excitation the intended answer, although the general emf relation also includes speed.
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