AC electric motors operate by applying alternating current (AC) power to the electric motor. The main parts of AC electric motors are the stator and rotor. The AC electric motors’ stator consists of coils that are supplied with alternating current power and produce a rotating magnetic field. AC electric motors rotor will rotate inside the electric motor coils and the output shaft produces torque via the rotating magnetic field.
There are two different types of AC electric motors and each of them uses a different type of rotor. The first type of AC motor is called an induction motor. Induction motors use a magnetic field on the rotor of an induction motor that’s created by an induced current. The other type of AC motor is called a synchronous motor and rotates precisely at the supply frequency or on a sub-multiple of the supply frequency. Synchronous motors are able to operate with precision supply frequency because it doesn’t reply on an induced current. The magnetic field on a synchronous motor is generated by current delivered through slip rings or a permanent magnet. Synchronous motors run faster than induction motors because the speed is reduced by the slip of asynchronous motors.
AC Electric Motors With Variable FrequencyDrives
Over the past decade, AC electric motors have been paired with variable frequency drives as a cost efficient way to reduce power costs and increase system production efficiency. Approximately one third of the world’s electrical energy is supplied by electric motors in fixed-speed centrifugal pump, fan, and air compressor applications. These fixed-speed applications don’t always require the full load speed (RPM) of the electric motor in which they’re operating. By installing a variable frequencydrive to these AC electric motor applications, the motor speed is reduced, and power costs can be reduced by 50% or more.This energy savings is often significant enough to cover the cost of a variable frequency drive within a few months.
Pairing AC electric motors with variable frequency drives is common in many applications such as swimming pool pumps, air compressors, conveyor belts, lathes, mills, food processing, plastic extrusion, waste water treatment pumps, HVAC fans and blowers, and many more. AC electric motors and variable frequencydrivesare used on machinery to increase or decrease the acceleration and deceleration times on alternating current (AC) motors.
Adjusting the acceleration and deceleration time of AC electric motors can extend the motor’s lifespan, and can also improve efficiency on production demands. Variable frequency drives on AC electric motorscan also provide the ability to control the frequency of starting and stopping an AC motor.This ability provides a means by which AC electric motors are only operating when needed for the equipment they’rerotating. AC electric motors have a longer lifespan if they’re not continuously operating when they don’t need to be.