Consider the following statements about torque in synchronous motors. I. The torque in a synchronous motor is produced only when the rotor is locked into synchronism. II. The torque is directly proportional to the sine of the load angle (δ). III. Synchronous motor develops starting torque proportional to the power input. IV. Maximum torque occurs at δ = 180°. Which of the above statements are correct?
Statements I & II only
To determine the correct statements about torque in synchronous motors, let's evaluate each statement step by step:
- Statement I: The torque in a synchronous motor is produced only when the rotor is locked into synchronism.
- Statement II: The torque is directly proportional to the sine of the load angle (δ).
- Statement III: Synchronous motor develops starting torque proportional to the power input.
- Statement IV: Maximum torque occurs at δ = 180°.
Based on the above evaluations, the correct statements are Statement I and Statement II only.
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For a slip 's' and supply frequency 'f', the frequency of current in rotor will be-
The rotating magnetic field in a three-phase, 6-poles, 50 Hz slip ring induction motor will rotate at-
The synchronous speed of a three phase induction motor having 20 poles and connected to a 50 Hz source is-
The rotor current frequency in a slip-ring induction motor depends on-
The power factor of an induction motor operating at no load is around:
