Power factor

In alternating current power, the ratio of active power to apparent power is expressed by the following formula.

Active power / Apparent power
or
(Active power / Apparent power) × 100 (%)

It indicates the phase difference between the voltage waveform and the current waveform. If the current leads, it is called leading power factor; if it lags, it is called lagging power factor. The degree of lag is determined by the proportion of L (inductance) components in the electric circuit, and the degree of lead is determined by the proportion of C (capacitance) components. If there are no LC components, the power factor becomes 1 (100%). In power transmission and distribution circuits, it is required to increase the power factor to around 0.8 (80%) for efficient use of electric wires and to reduce losses. To improve a lagging power factor, power factor correction capacitors are grounded.