Answer 6
Power factor, in traditional usage, is defined as the ratio of "real" power-the average of instantaneous voltage multiplied by instantaneous current over one full cycle-to the "apparent" power that you get by multiplying RMS voltage by RMS current without regard to phase angle.

An ideal coil or capacitor consumes zero real power because although they carry significant current, it's at -90° or 90°, respectively, to the applied voltage. (Remember "ELI the ICE man?")

The reactive current causes problems in power distribution systems, because it causes real power dissipation in the wires, over and above the current required by resistive loads.

Contributor: David Tweed

Published July 2003