A traditional ceiling fan is an example of an induction motor, specifically a single-phase induction motor.
- Traditional ceiling fan: usually a single-phase induction motor, commonly a capacitor-run motor.
- The capacitor creates a phase difference between the main and auxiliary windings, producing a rotating magnetic field.
A single AC wire is enough to produce a magnetic field, but not a naturally rotating magnetic field.
Suppose we connect one coil to AC:
So the field simply gets stronger, weaker, and reverses direction. It does not continuously rotate around the motor.
Because of this, a single-phase induction motor has zero starting torque when stationary (in the ideal case).
Role of a Capacitor in a Ceiling Fan
A typical AC fan has two windings:
- Main winding → connected to AC
- Auxiliary winding → AC through a capacitor
The capacitor shifts the current in the auxiliary winding, creating a phase difference between the two magnetic fields.
So the fan effectively creates a rotating magnetic field for starting/running.