What Is the Definition of "power Factor"?

Power factor measures the efficiency of electrical output. It is the process of analyzing the use of electrical power within a facility’s electrical system. Power factor evaluates the relationship of the components of electrical power in a particular AC circuit. The components analyzed by the measure include real power, reactive power and apparent power.

The power factor is the ratio of real power used to do work to the apparent power supplied to the system or circuit. Power factors receive values between 0 and 1. When no real power is present, the power factor is 0. When all power is real and none is reactive, the power factor is 1. If a utility company’s power factor is less than 1, it must supply more current to the system or user to optimize output. A large power factor is desired, while a low power factor is the result of inefficient electrical power measurements.

Real or working power refers to the work-producing power used to run the system or equipment. Real power is the power utilized in electric heating, lighting and electric appliances. Real power is measured in kilowatts. Reactive power refers to the non-working producing power needed to magnetize and start the equipment. It is a type of inductive load and measured in kilovolt-amperes-reactive units. Apparent power is the product of amperes and volts of a circuit. Apparent power is measured in kilovolt-amperes and includes both working and reactive power measurements.