Why are capacitors used on motors?

The use of capacitors in motors, particularly in single-phase induction motors, primarily revolves around the enhancement of starting torque. Motors typically require a certain amount of torque to start turning, and for single-phase motors, this is often insufficient to initiate movement efficiently.

By introducing a capacitor in the circuit, the phase angle between the voltage and current is altered. This phase shift effectively creates a secondary winding effect, allowing the motor to generate a stronger magnetic field during startup. The lagging power factor introduced by the capacitor results in improved torque during the initial rotation, enabling the motor to overcome inertia and start effectively.

While the other options touch on different aspects of motor operation, they do not directly address the primary function of capacitors in relation to motor starting torque. For instance, while a constant current supply is important for electrical systems, capacitors do not provide this supply directly; they store energy and release it as needed. Capacitors can help in voltage regulation but are not primarily for increasing voltage levels. Their role in preventing overheating is also relevant but secondary to their primary function in enhancing starting torque.