Electrical Machines
Cogging and crawling are phenomena associated with

 cage induction machines and they are essentially the same.
 the former during starting and the latter at a fraction of its rated speed.
 the former at a fraction of its rate speed and the latter during starting.
 any of the above.

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

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

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