Editing Power factor (section)

==== Passive PFC ====
The simplest way to control the [[Harmonics (electrical power)|harmonic]] current is to use a [[electronic filter|filter]] that passes current only at [[utility frequency|line frequency]] (50 or 60&nbsp;Hz). The filter consists of capacitors or inductors and makes a non-linear device look more like a [[linear]] load. An example of passive PFC is a [[valley-fill circuit]].

A disadvantage of passive PFC is that it requires larger inductors or capacitors than an equivalent power active PFC circuit.<ref>{{Citation |url=http://www.nuvation.com/corporate/news/newsletter/fall2006/powersupply.html |publisher=Nuvation |date=Fall 2006 |title=Power Supply Design Principles: Techniques and Solutions, Part 3 |newspaper=Newsletter |first=Ben |last=Schramm |url-status=dead |archive-url=https://web.archive.org/web/20070309134617/http://www.nuvation.com/corporate/news/newsletter/fall2006/powersupply.html |archive-date=2007-03-09 }}</ref><ref>{{Citation | newspaper = Xplore | title = Quasi-active power factor correction with a variable inductive filter: theory, design and practice | volume = 18 | issue = 1 | pages = 248–255 | publisher = IEEE| doi = 10.1109/TPEL.2002.807135 | bibcode = 2003ITPE...18..248W | year = 2003 | last1 = Wolfle | first1 = W.H. | last2 = Hurley | first2 = W.G. }}</ref><ref>{{Citation |publisher=Nuigalway |type=project |url=http://www.nuigalway.ie/power_electronics/projects/quasi_active.html |place=[[Ireland|IE]] |title=Power electronics |contribution=Quasi-active Power Factor Correction: The Role of Variable Inductance |last1=Wölfle |first1=W. H. |last2=Hurley |first2=W. G. |access-date=2008-11-05 |archive-date=2020-08-06 |archive-url=https://web.archive.org/web/20200806105647/http://www.nuigalway.ie/power_electronics/projects/quasi_active.html |url-status=dead }}</ref> Also, in practice, passive PFC is often less effective at improving the power factor.<ref name="effi">{{Citation | url = http://www.xbitlabs.com/articles/coolers/display/atx-psu5_3.html | title = ATX Power Supply Units Roundup | publisher = xBit labs | quote = The power factor is the measure of reactive power. It is the ratio of active power to the total of active and reactive power. It is about 0.65 with an ordinary PSU, but PSUs with active PFC have a power factor of 0.97–0.99. […] hardware reviewers sometimes make no difference between the power factor and the efficiency factor. Although both these terms describe the effectiveness of a power supply, it is a gross mistake to confuse them. […] There is a very small effect from passive PFC – the power factor grows only from 0.65 to 0.7–0.75. | url-status = dead | archive-url = https://web.archive.org/web/20081120040707/http://www.xbitlabs.com/articles/coolers/display/atx-psu5_3.html | archive-date = 2008-11-20 }}</ref><ref>{{Citation|date=Mar 16, 2006 |publisher=Find articles |url=http://findarticles.com/p/articles/mi_m0EIN/is_2006_March_16/ai_n26797888 |archive-url=https://web.archive.org/web/20090901140721/http://findarticles.com/p/articles/mi_m0EIN/is_2006_March_16/ai_n26797888/ |url-status=dead |archive-date=September 1, 2009 |title=The Active PFC Market is Expected to Grow at an Annually Rate of 12.3% Till 2011 |quote=Higher-powered products are also likely to use active PFC, since it would be the most cost effective way to bring products into compliance with the EN standard. }}</ref><ref>{{Citation | url = http://www.techarp.com/showarticle.aspx?artno=81&pgno=1 | publisher = TECHarp | title = Power Factor Correction | quote = Passive PFC […] the power factor is low at 60–80%. […] Active PFC ... a power factor of up to 95%}}</ref><ref>{{Citation | publisher = Silverstone Technology | url = http://www.silverstonetek.com/tech/wh_pfc.php?area= | title = Why we need PFC in PSU | quote = Normally, the power factor value of electronic device without power factor correction is approximately 0.5. […] Passive PFC […] 70~80% […] Active PFC […] 90~99.9% | url-status = dead | archive-url = https://web.archive.org/web/20081222085515/http://www.silverstonetek.com/tech/wh_pfc.php?area= | archive-date = 2008-12-22 }}</ref><ref>{{Citation | publisher = Electronic products | newspaper = Taiyo | url = http://www2.electronicproducts.com/PFC_options_for_power_supplies-article-taiyo-mar2004-html.aspx | title = PFC options for power supplies | first = Tom | last = Brooks | date = Mar 2004 | quote = The disadvantages of passive PFC techniques are that they typically yield a power factor of only 0.60 to 0.70 […] Dual-stage active PFC technology [yields] a power factor typically greater than 0.98 | url-status = dead | archive-url = https://web.archive.org/web/20081202100831/http://www2.electronicproducts.com/PFC_options_for_power_supplies-article-taiyo-mar2004-html.aspx | archive-date = 2008-12-02 }}</ref>