Electrical Machines
Under which of the following conditions hunting of synchronous motor is likely to occur ?

  Periodic variation of load.
  Over-excitation.
  Over-loading for long period.
  Small and constant load.

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Electrical Machines
In case of 3 - Φ IM, plugging means

  starting the motor on load which is more than the rated load.
  locking of rotor due to harmonics.
  pulling the motor directly on line without a rotor.
  interchanging two supply phases for quick stopping.

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Electrical Machines
The synchronous motor can be started by

  coupling it with a small AC induction motor called the pony motor.
  any of the above methods.
  providing damper winding in its rotor circuit.
  coupling it with a DC compound motor.

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