What Is the Role of the Capacitor in Starting and Running a Ceiling Fan?
A ceiling fan uses a single-phase induction motor , which cannot start on its own because it produces no initial rotating magnetic field. This is where the capacitor becomes essential. It performs two major functions: 1. To Start the Fan: Creating a Rotating Magnetic Field Why a capacitor is needed for starting In a single-phase AC supply, the motor produces only an alternating magnetic field—not a rotating one. A rotating magnetic field is needed to start the rotor spinning. How the capacitor solves this The ceiling fan has two windings: Main winding and auxiliary (starting) winding The capacitor is connected in series with the auxiliary winding. The capacitor shifts the phase of the current in the auxiliary winding. Result The phase shift creates a second magnetic field , which is out of phase with the main one. These two fields combine to produce a rotating magnetic field that gives the fan the initial push to start. Without the capacitor, the fan wil...