Electrical Machines
The introduction of interpoles in between the main poles improves the performance of a dc machine, because

 the inequality of air-gap flux on the top and bottom halves of the armature is removed
 a counter-emf is induced in the coil undergoing commutation
 the interpoles produce additional flux to augment the developed torque
 the flux waveform is improved with reduction in harmonics

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Electrical Machines
In a DC machine, for the same value of φ, Z and N; which one of the following statements is correct?

  Armature emf is more with wave winding than with lap winding.
 Armature emf depends on weather the machine is running as a motor or generator.
 Armature emf is less with wave winding than with lap winding.
 Armature emf is same as long as the flux density in the air gap remains the same.

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