# Power Factor

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Related to Power Factor: reactive power

## power factor

[′pau̇·ər ‚fak·tər] (electricity)

The ratio of the average (or active) power to the apparent power (root-mean-square voltage times rms current) of an alternating-current circuit. Abbreviated pf. Also known as phase factor.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

The following article is from

*The Great Soviet Encyclopedia*(1979). It might be outdated or ideologically biased.## Power Factor

(cos ɸ), the ratio of the average power of alternating current to the product of the effective values of voltage and current. The maximum value of the power factor is 1. For a sinusoidal alternating current, the power factor is equal to the angle of the phase shift between the sine curves of voltage and current and is determined by the circuit parameters: cos ɸ = *r/Z*, where ɸ is the phase shift angle, *r* is the effective resistance of the circuit, and Z is the total impedance. The power factor may have a value different from 1 even in circuits containing only resistances, if the circuits contain any nonlinear sections. In this case the power factor is decreased because of the distorted shape of voltage and current curves.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

## power factor

In an alternating current, the ratio of the average power (expressed in watts) to the apparent power (expressed in volt-amperes).

McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.