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

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

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
In a DC machine

 current and emf in armature are unidirectional
 emf in armature conductors and at the terminals is alternating.
 current and emf in armature are alternating.
 current and emf at the terminals are alternating.

ANSWER DOWNLOAD EXAMIANS APP

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

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

ANSWER DOWNLOAD EXAMIANS APP