Directly connected to supply

Connected in series with armature

Connected in parallel with armature

Connected in series with shunt field

Field control method

Armature control method

Tapped field speed control

Ward Leonard speed control

Incorrect brush position

Incorrect field connection

Incorrect direction of rotation

Incorrect armature connection

Assists the applied voltage

Opposes the applied voltage

Increases the armature current

Decreases the armature current

Limit current in NVC

Protect the coil from short circuit

Protect the motor from overload

Protect the armature from short circuit