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

  None of above.
  Any of above method.
  Ward Leonard control.
  Rheostatic control.

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Electrical Machines
A dc shunt generator, when commissioned after a major repair of the field system, failed to build Up voltage. It was because

 there was a break in the armature circuit
 field winding was wrongly connected
 field system lost residual magnetism
 field resistance was higher than critical resistance

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

 the interpoles produce additional flux to augment the developed torque
 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 flux waveform is improved with reduction in harmonics

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Electrical Machines
If two 8-pole dc machines of identical armature sare wound, one with lap winding and the other with wave winding, then

 wave-wound machine will have more rated current and more voltage
 lap-wound machine will have more rated voltage and more current
 lap-wound machine will have more rated voltage and less current
 wave-wound machine will have more rated voltage and less current

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