Electrical Machines
The main disadvantage(s) of the ward-Leonard system is/are

 high initial cost.
 high maintenance cost.
 all of above.
 poor overall efficiency.

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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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