Limit the field cur

Limit the field voltage

Control the motor speed

Limit the armature current

Megger

Growler

Multimeter

Ohmmeter

To limit the load current

To run motor at low voltage

To hold the handle plunger firmly

To protect the motor from high speed

Change armature current direction

Change shunt field current direction

Change series field current direction

Change the current in armature and shunt field together

To improve the torque

Reduce the field current

To decrease the back emf

To prevent increase in speed