AS9120B, ISO 9001:2015, and FAA AC 0056B ACCREDITED

What is an AC Motor?

Engineers and designers have been using AC motors for years. Several essential appliances, equipment, and tools that we use in our daily lives are powered by an AC motor. An AC motor provides flexibility and efficiency that makes it ideal for machinery applications.

The AC motor is an electric motor that uses alternating current and magnetism to produce mechanical energy. The stator has a series of coils supplied with alternating current that creates a rotating magnetic field inside a rotor, leading to the establishment of a second magnetic field connected to the output shaft.

How Does The AC Motor Work?

The AC motor consists of two main components. First, the stator, which is the stationary outer drum of the motor, and the second rotor, located in the inner portion of the motor attached to the motor shaft. During operations, both produce rotating magnetic fields. In simple words, there are two pairs of electromagnet coils forming a stator. They are connected to an AC power supply which produces a current inside the rotor. The produced current generates its magnetic field and opposes another magnetic field produced by the stator.

The interaction between these two magnetic fields makes the rotor turn. The AC current does not go on and off but instead rises and falls in the shape of a sine wave. The rotating magnetic field created by this process alternates between the coils, causing the motor to rotate at the same speed (in theory) as the current supply.

Types Of AC Motors

The main difference between each version falls under the type of electrical feed such as single-phase, double phase, or three-phase.

  • Single Phase AC Motor

The single-phase AC motor is an excellent choice when powering just one or two devices. As the name suggests, the stator only requires single-phase electricity to operate. Single-phase motors are relatively small and cheaper than their three-phase counterparts.

  • Polyphase AC Motor

While similar to single-phase motors in their operation, Polyphase Motors require two or three-phase electricity and produce 1.5 times more output. Also, the polyphase system has a constant current.

  • Synchronous AC Motor

Synchronous motors are unique in that they have a distinct advantage over other types of electric motors. They can handle high amounts of power with a slight loss, primarily due to their very particular design, which allows for constant speeds regardless of a variable input load.

  • Repulsion Motor

A repulsion motor is a type of single-phase motor. A repulsion motor's working principle and function is the repelling or pushing away of magnetic fields from one another. The additional commutator brush assembly helps create this effect by enabling electric current flow in only one direction through each phase winding while preventing it from flowing backward.

Why Do We Use AC Motors?

AC motors are the perfect choice for any application that needs a flexible and efficient machine. Their low noise level makes them ideal in applications like pumps, water heaters, or ovens.

The following are some significant reasons to use an AC motor:

  • Efficiency – AC motors convert about 85% of incoming energy into valuable mechanical energy, and they can run at high speeds without overheating, braking, or degenerating.
  •  Lifespan – AC motors demand minimal maintenance while remaining highly durable in rigorous conditions.
  •  Accessibility – AC motors come in different shapes, sizes, and power outputs, so you can easily customize them or make a custom design if needed.
  • Speed Regulation – One can easily control the speed of an AC motor by changing the current frequency to speed up or slow down.
  • Single-phase Input – the motor runs from a single-phase unit to a three-phase unit. Hence, it is used in both simple operations and heavy-duty areas.

How AC Motors Are Made

There are three main components of an AC motor:

  1. Rotor
  2. Stator
  3. Housing

Parts of an AC Motor

  • Stator Core

The stator is the fixed part of an AC motor, and it is made up of laminations which are thin metal sheets that form a cylinder. The use of these materials is to reduce energy loss.

  • Stator Windings

The stationary part of the motor is the stator winding, wrapped with copper wires in slots. Slots are defined based on the phases of power provided to the coils.

  •  Rotor

The root is an internal part of the AC motor which rotates. The most common type of rotor used is the squirrel cage rotor. Once the rotor is ready and the conductor bars are inserted, a steel shaft is pushed into the center of the assembly.

  • Bearings

Bearings support and locate the rotor while minimizing the air gap and transferring loads to the motor. They can operate at any speed with minimum friction.

  • Air Gap

The air gap is the space between the stator and rotor. More air gap length helps in generating less noise.


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February 19, 2023
December 2, 2022

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