Variable Speed Motor
A variable speed motor uses VFDs, or variable-frequency drives, to direct the rotational speed of an AC motor.
A variable speed motor will do this by controlling the frequency of the power being supplied to the motor. The motor itself can be a single-phase unit, but three-phase induction motors are most commonly used in variable speed motors.
A variable speed motor is often used in heating and cooling ventilation applications. In such applications, the motor gradually increases to meet its maximum speed rather than starting at its maximum (and only) speed, like fixed speed motors. This progressive movement towards high speed eliminates noisy startup sound and reduces wear on components. The variation of speed also allows for precise control of airflow.
A variable speed electric motor is used in a wide variety of applications in almost every industry because they are cleaner and less expensive to run than fuel-powered motors. Because of their efficiency, variable speed motors also use less electricity on average than a fixed speed motor.
A variable speed electric motor will create no waste emissions and improve air quality.