Electrical Machines
A 230 volt dc motor has an armature winding resistance of 0.5 ohm. Calculate the emf induced by the motor if the full load armature current is 23 ampere.

  120 volt.
  None of these.
  218.5 volt.
 220.4 volt.

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Electrical Machines
In a dc generator operating on load with its brushes on the geometrical neutral axis (GNA), the magnetic neutral axis (MNA) is shifted in the direction of rotation. Now, if the brushes are given a lead of 90° (electrical), then the MNA will

 coincide with the GNA
 shift forward by more than 90°
 shift forward by 90°
 shift forward by less than 90°

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Electrical Machines
For a given torque, reducing diverter resistance of a DC series motor causes

 increase in speed demanding more armature current.
 increase in speed but armature currnet remains the same.
 decrease in speed demanding less armature current.
 decrease in speed but armature current remains the same.

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