Editing Three Gorges Dam (section)

=== Generators ===
The main generators each weigh about 6,000&nbsp;tonnes and are designed to produce more than 700&nbsp;MW of power each. The designed [[hydraulic head]] of the generators is {{convert|80.6|m}}. The flow rate varies between {{convert|600|-|950|m3/s}} depending on the head available; the greater the head, the less water needed to reach full power. Three Gorges uses [[Francis turbine]]s with a diameter of 9.7/10.4&nbsp;m (VGS design/Alstom's design) and a rotation speed of 75&nbsp;revolutions per minute. This means that in order to generate power at 50&nbsp;[[Hz]], the generator rotors have 80 poles. Rated power is 778 [[Volt ampere|MVA]], with a maximum of 840&nbsp;MVA and a [[power factor]] of 0.9. The generator produces electrical power at 20&nbsp;[[Volt|kV]]. The electricity generated is then stepped up to 500&nbsp;kV for transmission at 50&nbsp;Hz. The generator's [[stator]], the biggest of its kind, is 3.1/3&nbsp;m in height; the outer diameter of the stator is 21.4/20.9&nbsp;m, the inner diameter is 18.5/18.8&nbsp;m, and the bearing load is 5,050/5,500 tonnes. Average efficiency is over 94%, with a maximum efficiency of 96.5% reached.<ref>{{cite news |date=August 28, 2008 |agency=Xinhua News Agency |access-date=December 6, 2008 | language=zh |archive-date=December 7, 2008 |script-title=zh:李永安:我水轮发电机组已具完全自主设计制造能力_财经频道_新华网 | trans-title=Li Yongan: Our hydroelectric generator set has completely independent design and manufacture capabilities | url=http://news.xinhuanet.com/fortune/2008-08/28/content_9723523_2.htm |archive-url=https://web.archive.org/web/20081207040501/http://news.xinhuanet.com/fortune/2008-08/28/content_9723523_2.htm  |url-status=dead}}</ref><ref>{{cite web |archive-date=March 7, 2012 |first1=Matthew |last1=Morioka |url=http://www.eng.hawaii.edu/~panos/444_09_4_9.pdf |title=Three Gorges Dam |access-date=February 2, 2017 |archive-url=https://web.archive.org/web/20120307101739/http://www.eng.hawaii.edu/~panos/444_09_4_9.pdf |last2=Abrishamkar |first2=Alireza |last3=Kay |id=CEE 491 |first3=Yve |url-status=live |website=eng.hawaii.edu}}</ref>
[[File:Sanxia Runner04 300.jpg|thumb|upright=1.1|[[Francis turbine]] at Three Gorges Dam]]

The generators were manufactured by two joint ventures: [[Alstom]], [[ABB]], [[Kvaerner]], and the Chinese company Harbin Motor; and [[Voith]], [[General Electric]], [[Siemens]] (abbreviated as VGS), and the Chinese company Oriental Motor. The technology transfer agreement was signed together with the contract. Most of the generators are water-cooled. Some of the newer ones are air-cooled, making them simpler in design and easier to manufacture and maintain.<ref name="Chinacom20020726">{{cite news  |url=http://www.chinaccm.com/23/2307/230701/news/20020726/105549.asp |title=三峡工程及其水电机组概况 |publisher=中华商务网讯 |date=July 26, 2002 |access-date=April 11, 2008 | language=zh |archive-url=https://web.archive.org/web/20081207034132/http://www.chinaccm.com/23/2307/230701/news/20020726/105549.asp |archive-date=December 7, 2008 |trans-title=Three Gorges Project and water and electricity unit survey |url-status=dead}}</ref>