DEFINITION: POWER FACTOR

Power Factor: In alternating-current power transmission and distribution, the cosine (relationship) of the phase angle* between the voltage and current. Note 1: When the load is inductive, e.g., an inductive motor, the current lags the applied voltage, and the power factor is said to be a lagging power factor. When the load is capacitive, e.g., a synchronous motor or a capacitive network, the current leads the applied voltage, and the power factor is said to be a leading power factor. Note 2: Power factors other than unity have deleterious effects on power transmission systems, including excessive transmission losses and reduced system capacity.

The highest power factor rating for alternating-current is a 1.0 rating. This correct power factor is also referred to as "unity" or a 100% power factor. "Unity" power has many advantages over lower power factor ratings; and is critically important to power distortion reduction as well as frequency regulation. PF 1.0 is important for properly operating induction motors and is critical when operating equipment which utilize electronic controls.

*phase angle: Of a periodic wave, the number of suitable units of angular measure between a point on the wave and a reference point. Note 1: The reference point may be a point on another periodic wave. The waves may be plotted on a suitable coordinate system, such as a Cartesian plot, with degrees or other angular measure usually plotted on the abscissa and amplitude on the ordinate. Usually, at least one full cycle of each wave is plotted with 360 & 176; (2 pi radians) encompassing one full cycle. The reference points may be any significant instants on the waves, such as where they cross the abscissa axis. Note 2: The use of angular measure to define the relationship between a periodic wave and a reference point is derived from the projection of a rotating vector onto the real axis of an Argand diagram. Note 3: The value of the phase angle of a point on the wave is the point on the abscissa that corresponds to the point on the wave.