Electrical Machines
For very sensitive and wide speed control, the preferable control method is

 Field control.
 Ward-Leonard control.
 Multiple voltage control.
 Armature control.

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

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

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