What is the working principle of ceiling fan?

The celing fan motor works on principle of single phase
induction motor using capacitor.
Working of capacitor start motor: The stator consists of
the main winding and a starting winding (auxiliary). The
starting winding is connected in parallel with the main
winding and is placed physically at right angles to it. A
90-degree electrical phase difference between the two
windings is obtained by connecting the auxiliary winding in
series with a capacitor and starting switch. When the motor
is first energized, the starting switch is closed. This
places the capacitor in series with the auxiliary winding.
The capacitor is of such value that the auxiliary circuit
is effectively a resistive-capacitive circuit (referred to
as capacitive reactance and expressed as XC). In this
circuit the current leads the line voltage by about 45°
(because XC about equals R). The main winding has enough
resistance-inductance (referred to as inductive reactance
and expressed as XL) to cause the current to lag the line
voltage by about 45° (because XL about equals R). The
currents in each winding are therefore 90° out of phase -
so are the magnetic fields that are generated. The effect
is that the two windings act like a two-phase stator and
produce the rotating field required to start the motor.
When nearly full speed is obtained, a centrifugal device
(the starting switch) cuts out the starting winding. The
motor then runs as a plain single-phase induction motor.
Since the auxiliary winding is only a light winding, the
motor does not develop sufficient torque to start heavy
loads. Split-phase motors, therefore, come only in small
sizes.