Electrical Machines
The speed of a cumulatively compound DC motor can be controlled by varying

 Armature voltage control.
 Armature resistance control.
 Any of above.
 Shunt field resistance control.

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Electrical Machines
In large sized DC machines the compensating windings are provided to

 reduce eddy current losses by providing local short circuits.
 compensate for the decrease in speed due to increase of load.
None of these
  neutralize voltage induced in coil due to fluctuation of l

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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

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

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