Electrical Machines
To have sparkless commutation, the armature reaction effect in a DC machine is neutralized by

 increasing field excitation.
 fixing the brush axis inline with the pole axis.
 shifting the brush axis from GNA to MNA.
  compensating winding and commutating poles.

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Electrical Machines
Which of the following represents the commutator pitch?

 Number of conductors spanned by one coil at the front end of the armature.
 The distance between the staring of first coil and its next successive coil
 Number of commutator segments between two successive coils.
 Number of conductors spanned by one coil at the back end of the armature.

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