Electrical Machines
Which of these types of motor is used in elevators?

 None of these.
 DC compound motor.
 DC series motor.
 DC shunt motor.

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Electrical Machines
Interpoles in a DC motor must be

 Shunt excited and should have the same polarity as that of the ahead main pole in the direction of rotation of armature.
 Series excited and should have the same polarity as that of the ahead main pole in the direction of rotation of armature.
 Shunt excited and should have the same polarity as that of the behind main pole in the direction of rotation of armature.
 Series excited and should have the same polarity as that of the behind main pole in the direction of rotation of armature.

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Electrical Machines
In DC machines, the interpoles are provided

  to make commutation spark less.
 to counteract the reactance voltage and the cross-magnetizi
 to counteract demagnetizing effect of armature mmf in commutating zone.
  both (B) and (C).

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