Build up the voltage

Reduce the field current

Reduce armature current

Maintain constant output voltage

Resistance between the opposite brushes

Resistance between brush and commutator raiser

Resistance between brush and commutator

Resistance between brush and armature conductors

Long shunt compound

Cumulative compound

Differential compound

Short shunt compound

Reduce the copper loss

Reduce the friction loss

Reduce the hysteresis loss

Reduce the eddy current loss

Reduce armature current

Reduce armature voltage drop

Run armature with less weight

Reduce the temperature of armature