What is the power factor in an electrical circuit?

The power factor is the ratio of real power to apparent power in an electrical circuit.

In an AC circuit, the power factor is a measure of how efficiently the circuit is using the supplied power. It is defined as the ratio of the real power (measured in watts) to the apparent power (measured in volt-amperes). Real power is the power that is actually consumed by the circuit and is used to perform useful work, such as powering a motor or lighting a bulb. Apparent power is the product of the voltage and current in the circuit and represents the total power that is being supplied to the circuit.

A power factor of 1 indicates that the circuit is using all of the supplied power to perform useful work, while a power factor of less than 1 indicates that some of the supplied power is being wasted. This can occur when the circuit contains reactive components, such as capacitors or inductors, which store energy and release it back into the circuit. This reactive power does not perform useful work and can cause the voltage and current to become out of phase, reducing the power factor.

Improving the power factor can reduce energy consumption and improve the efficiency of the circuit. This can be achieved by adding power factor correction devices, such as capacitors or inductors, to the circuit. These devices can offset the reactive power and improve the power factor, resulting in a more efficient use of the supplied power.