Using compensating winding

Providing additional inter poles

Increasing brush contact resistance

Adding resistance wires with winding

Field coil resistance increases

Armature resistance increases

Increase the armature reaction

Looses its residual magnetism

160V

320V

480V

640V

Induced emf increases

Induced emf decreases

No change in induced emf

Induced emf becomes zero

Short circuit in field winding

Short circuit in armature winding

MNA and GNA position changed

Too much spring tension at brush