Electrical Machines
To get the speed of DC motor more than normal without wastage of electrical energy _____________ is used.

 rheostatic control.
 none of above.
 Ward Leonard control.
 any of above method.

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Electrical Machines
Which of the following represents the commutator pitch?

 Number of conductors spanned by one coil at the back end of the armature.
 Number of conductors spanned by one coil at the front end of the armature.
 The distance between the staring of first coil and its next successive coil
 Number of commutator segments between two successive coils.

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Electrical Machines
In a synchronous motor when the rotor speed exceeds the synchronous speed during hunting

  the damper bars develop induction generator torque.
  the damper bars develop synchronous motor torque.
  the damper bars develop induction motor torque.
  negative sequence currents are generated.

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