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

  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.
  pulling the motor directly on line without a rotor.

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Electrical Machines
If the frequency of input voltage of a transformer is increased keeping the magnitude of voltage unchanged, then

 Ph will decrease but Pe will remain same
 both hysteresis loss(Ph) and eddy current loss(Pe) will increase
 Pe will increase but Ph will decrease
 Ph will increase but Pe will decrease

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