Permanent Magnet DC Motor is Preferable:
- When the Required speeds exceed the linked to the network frequency.
- When a battery or accumulator power supply is required.
- When a high drive torque is required.
- When speed variation is required without resorting to expensive electronics.
Asynchronous AC Motor is Preferable:
- When fixed speeds determined by the frequency of power supply network can be used (e.g. 2800,1400,950 rpm)
- When higher speed stability is required.
- When an inverter can be fitted for continuous speed change.
- When the motor is exposed to heavy duty,thus reducing maintenance.