Electrical Machines
Which of the following is/are the advantages of carbon brush over the copper brush?

 They are self lubricating in nature
 They are not hard as copper brush
All of these
 In case of any sparking they will be less damaged than copper brushes

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Electrical Machines
In DC machines, the interpoles are provided

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

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