Elevators

Paper rolling mills

AC to DC converter

Power factor correction device

Noiseless

High efficiency

Low maintenance required

DC output voltage can be easily controlled

Produce high voltage to initiate the rotation

Produce high current to start rotate the motor

Produces torque and runs near in synchronous speed

Produce a high magnetic-field to maintain a constant speed

Insufficient excitation

Defective pony motor

Open in damper winding

Short in damper

Varying the motor load

Varying the rotor excitation

Varying stator voltage in motor

Varying stator current in motor