Why is the capacitor used in a fan?

A capacitor is used in a fan for various reasons, depending on the type of motor used in the fan. The most common type of motor used in fans is the single-phase induction motor, and capacitors play a crucial role in its operation.

In a single-phase induction motor, the main winding is used to create a rotating magnetic field that drives the rotor. However, due to the single-phase power supply, the rotating magnetic field alone cannot provide enough torque to start the motor from a standstill. This is where a capacitor comes into play.

Start Capacitor: In many single-phase induction motors, a start capacitor is used in conjunction with the main winding. The start capacitor is connected in series with the auxiliary winding of the motor. When the motor is initially switched on, the capacitor helps create a phase shift between the main winding and the auxiliary winding. This phase shift creates a rotating magnetic field that initiates the motor's rotation. Once the motor reaches a certain speed, a centrifugal switch disconnects the start capacitor, and the motor continues to run using the main winding alone.

Run Capacitor: In some fans, particularly ceiling fans, a run capacitor is also used. The run capacitor is connected in parallel with the main winding. It helps improve the motor's performance by providing an additional phase shift and improving the motor's power factor. The run capacitor helps increase the motor's efficiency, reduce power consumption, and enhance the overall performance of the fan.

Overall, capacitors are used in fans to aid in starting the motor, improve its efficiency, and enhance its performance by creating the necessary phase shifts in the motor's windings.