What does the term "power factor" refer to in electrical systems?

Power factor is a crucial concept in electrical systems that quantifies the efficiency with which electrical power is converted into useful work output. It is defined as the ratio of real power to apparent power in a circuit. Real power, measured in watts (W), represents the actual power that performs work in the circuit, such as lighting a bulb or running a motor. Apparent power, measured in volt-amperes (VA), is the product of the circuit voltage and current, representing the total power flowing in the circuit.

The power factor provides insight into how effectively the electrical power is being used. A power factor of 1 (or 100%) indicates that all the power supplied is being utilized effectively for productive work. When the power factor is less than 1, it suggests that some of the power is not contributing to useful work, often due to the presence of reactive power in the circuit, which can occur with inductive or capacitive loads.

Understanding power factor is vital for the design and operation of electrical systems, as a low power factor can lead to higher energy costs, increased losses in the electrical system, and may require utilities to impose penalties or supply extra capacity to support the reactive power needed by inductive loads.