Output voltage increases

Output voltage decreases

Output voltage is pulsating

Output voltage will become zero

178 V

243 V

357 V

428 V

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