Limit current in NVC

Protect the coil from short circuit

Protect the motor from overload

Protect the armature from short circuit

To regulate field voltage

To carry the load current

To keep maximum inductance

To reduce the armature reaction

Shunt motor

Series motor

Cumulative compound motor

Differential compound motor

Constant load requirements

Constant speed requirements

High starting torque requirements

Constant speed under varying load requirements

Limit the field cur

Limit the field voltage

Control the motor speed

Limit the armature current