armature current and emf

armature current and terminal voltage

load current and terminal voltage

field current and terminal voltage

to collect current from the commulator

to facilitate collection of current from the armature conductors

to convey the current from the brushes to the holder

to prevent the brush from flying out under the centrifugal force

Rough commutation

Cross magnetizing effect

Demagnetizing effect

Armature resistance drop effect

Neutralisation of statically induced voltage

To make sparkless commutator

To change rough to smooth commutation

All of the above

D.C. shunt generator

D.C. series generator

D.C. Differential compound generator

D.C. cumulative compound generator