Fans with AC asynchronous motors

Asynchronous motors are alternating current electric motors in which the angular speed of the rotor is lower than the rotation speed of the magnetic field generated by the stator windings, hence the term asynchronous. Asynchronous motors are also called induction motors. The motor consists of a fixed part called the stator and a moving part called the rotor.

The stator is formed by a stack of plates arranged in the form of a circular crown. The grooves in the stack of stator plates host conducting enamelled copper wire windings, which can be arranged as three-phase or two-phase, depending on the type of alternating current supply.

The rotor is located inside the stator, and consists of another stack of plates in the form of a circular crown. This has a hole through it for the rotation shaft, and external grooves, or rotor slots, to accommodate the rotor winding. This can be of two types:

Wound-rotor (also called a slip ring-rotor)
Squirrel-cage rotor (also called a shorted rotor)