Power Factor
Power factor explained without the hand-waving: what causes it, what a poor one costs you, typical values by load type, and how correction works.
Questions people ask
Can power factor be greater than 1?
No. Real power can never exceed apparent power, so the ratio caps at 1. A meter reading above 1 is a measurement error.
How does capacitor correction work?
Capacitors draw a leading current that cancels part of the motor's lagging current. The reactive component largely circulates between the two instead of coming from the supply.
What power factor should I assume if I do not know it?
0.8 is the usual default for motor loads and the figure most sizing calculations start from. Use 1.0 for pure heating.
Does this page work offline?
Yes, after the first visit. The service worker caches it, so the reference stays available with no connection.
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Last updated 22 August 2026