Electrical Machines
In case the conditions for maximum power for DC motor are established, the efficiency of the motor will be

 Around 100 %.
 Any where between 75 % and 90 %.
 Around 90 %
 Less than 50 %

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

  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.
  interchanging two supply phases for quick stopping.

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Electrical Machines
Two of supply terminals to a 3 - Φ induction motor get interchanged during re-connection after normal maintenance. When switched on the supply, the motor will

  rotate in direction opposite to that before maintenance.
  rotate in the same direction as before maintenance.
  not start at all.
  get heated and damaged.

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