Editing Three-phase electric power (section)

== Three-phase loads ==
{{See also|Industrial and multiphase power plugs and sockets}}
[[File:3phase-rmf-noadd-60f-airopt.gif|thumbnail|right|Three-phase electric machine with rotating magnetic fields]]
An important class of three-phase load is the [[electric motor]]. A three-phase induction motor has a simple design, inherently high starting torque and high efficiency. Such motors are applied in industry for many applications. A three-phase motor is more compact and less costly than a single-phase motor of the same voltage class and rating, and single-phase AC motors above {{cvt|10|hp|lk=in}} are uncommon. Three-phase motors also vibrate less and hence last longer than single-phase motors of the same power used under the same conditions.<ref>{{cite book |last1=Alexander |first1=Charles K.|last2=Sadiku |first2=Matthew N. O.|date=2007 |title=Fundamentals of Electric Circuits |page=504|location=New York |publisher=McGraw-Hill |isbn=978-0-07-297718-9 }}</ref>

Resistive heating loads such as electric [[boiler]]s or space heating may be connected to three-phase systems. Electric lighting may also be similarly connected.

Line frequency flicker in light is detrimental to [[high-speed camera]]s used in sports event broadcasting for [[slow-motion]] replays. It can be reduced by evenly spreading line frequency operated light sources across the three phases so that the illuminated area is lit from all three phases. This technique was applied successfully at the 2008 Beijing Olympics.<ref name=3phlight>{{cite web|last=Hui|first=Sun|title=Sports Lighting&nbsp;– Design Considerations For The Beijing 2008 Olympic Games|url=http://www.geappliances.com/email/olympic_specifier/downloads/SportsLightinginBeijing2008OlympicGames.pdf|publisher=GE Lighting|access-date=18 December 2012|archive-date=28 April 2015|archive-url=https://web.archive.org/web/20150428120243/http://www.geappliances.com/email/olympic_specifier/downloads/SportsLightinginBeijing2008OlympicGames.pdf|url-status=dead}}</ref>

[[Rectifier]]s may use a three-phase source to produce a six-pulse DC output.<ref>{{cite journal |title=ACSL/Graphic Modeller Component Models for Electric Power Education |first1=Steven |last1=Pekarek |first2=Timothy |last2=Skvarenina |date=November 1998 |volume=41 |issue=4 |journal=IEEE Transactions on Education |url=http://www.ewh.ieee.org/soc/es/Nov1998/08/CONVERTR.HTM |archive-url=https://web.archive.org/web/20030626035019/http://www.ewh.ieee.org/soc/es/Nov1998/08/CONVERTR.HTM |url-status=dead |archive-date=June 26, 2003 |doi=10.1109/TE.1998.787374 |page=348 |bibcode=1998ITEdu..41..348P }}</ref> The output of such rectifiers is much smoother than rectified single phase and, unlike single-phase, does not drop to zero between pulses. Such rectifiers may be used for battery charging, [[electrolysis]] processes such as [[aluminium production]] and the [[electric arc furnace]] used in [[steelmaking]], and for operation of DC motors. [[Zigzag transformer]]s may make the equivalent of six-phase full-wave rectification, twelve pulses per cycle, and this method is occasionally employed to reduce the cost of the filtering components, while improving the quality of the resulting DC.

[[File:Perilex Stecker.jpg|thumb|right|[[Perilex|Three-phase plug]] used in the past on electric stoves in Germany]]

In many European countries electric stoves are usually designed for a three-phase feed with permanent connection. Individual heating units are often connected between phase and neutral to allow for connection to a single-phase circuit if three-phase is not available.<ref>[https://books.google.com/books?id=O3gnAAAAMAAJ&q=%22full+size+cookers+for+Europe+have+to+be+connected+to+a+three-phase+star+connected+supply%22 "British and European practices for domestic appliances compared"], ''Electrical Times'', volume 148, p. 691, 1965.</ref> Other usual three-phase loads in the domestic field are [[tankless water heating]] systems and [[storage heater]]s. Homes in Europe have standardized on a nominal 230&nbsp;V&nbsp;±10% between any phase and ground. Most groups of houses are fed from a three-phase street transformer so that individual premises with above-average demand can be fed with a second or third phase connection.