Electrical Machines
Which of the following is done in speed control of DC motor by field flux control?

 Inserting an additional resistance in the field circuit.
 Inserting resistance to armature circuit and field circuit.
 Any of above.
 Inserting an additional resistance in the armature circuit.

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Electrical Machines
In large sized DC machines the compensating windings are provided to

None of these
 compensate for the decrease in speed due to increase of load.
 reduce eddy current losses by providing local short circuits.
  neutralize voltage induced in coil due to fluctuation of l

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Electrical Machines
Cogging of induction motor occurs at

 low voltage and when stator and rotor poles are equal.
 high voltage and when stator and rotor poles are not equal.
 low voltage and when stator and rotor poles are not equal.
 high voltage and when stator and rotor poles are equal.

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