Synchronous motors are generally not self-starting because:
Correct answer: B. the direction of instantaneous torque reverses after half cycle
- A. the direction of rotation is not fixed
- B. the direction of instantaneous torque reverses after half cycle
- C. startes cannot be used on these machines
- D. starting winding is not provided on the machines
Explanation
At standstill, the synchronous rotor cannot follow the rapidly reversing stator field. The instantaneous torque reverses every half cycle, so its average starting torque is zero.
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