Electrical Machines
A dc shunt motor has external resistance Ra and Rf in the armature and field circuits respectively. Armature current at starting can be reduced by keeping

 Rf maximum and Ra minimum
 Ra maximum and Rf minimum
 Ra maximum and Rf maximum
 Ra minimum and Rf minimum

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

  pulling the motor directly on line without a rotor.
  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.

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