Editing Power factor (section)

=== Non-sinusoidal components ===
In linear circuits having only sinusoidal currents and voltages of one frequency, the power factor arises only from the difference in phase between the current and voltage. This is ''displacement power factor''.<ref name="FuchsMasoum2015">{{cite book|author1=Ewald Fuchs|author2=Mohammad A. S. Masoum|title=Power Quality in Power Systems and Electrical Machines|url=https://books.google.com/books?id=wuGcBAAAQBAJ&pg=PA432|date=14 July 2015|publisher=Elsevier Science|isbn=978-0-12-800988-8|pages=432–|quote=The DPF is the cosine of the angle between these two quantities}}</ref>

Non-linear loads change the shape of the current waveform from a [[sine wave]] to some other form. Non-linear loads create [[harmonic]] currents in addition to the original (fundamental frequency) AC current. This is of importance in practical power systems that contain [[non-linear]] loads such as [[rectifiers]], some forms of electric lighting, [[electric arc furnace]]s, welding equipment, [[Switched-mode power supply|switched-mode power supplies]], variable speed drives and other devices. Filters consisting of linear capacitors and inductors can prevent harmonic currents from entering the supplying system.

To measure the real power or reactive power, a [[wattmeter]] designed to work properly with non-sinusoidal currents must be used.