Editing Rectifier (section)

==== High power: thyristors (SCRs) and newer silicon-based voltage sourced converters ====
{{main|Silicon controlled rectifier}}
[[File:Manitoba Hydro-BipoleII Valve.jpg|thumb|200px|Two of three high-power [[thyristor]] valve stacks used for long-distance transmission of power from [[Manitoba Hydro]] dams. Compare with mercury-arc system from the same dam-site, above.]]

In high-power applications, from 1975 to 2000, most mercury valve arc-rectifiers were replaced by stacks of very high power [[thyristor]]s, silicon devices with two extra layers of semiconductor, in comparison to a simple diode.

In medium-power transmission applications, even more complex and sophisticated [[voltage sourced converter]] (VSC) silicon semiconductor rectifier systems, such as [[IGBT transistor|insulated gate bipolar transistors (IGBT)]] and [[Gate turn-off thyristor|gate turn-off thyristors (GTO)]], have made smaller high voltage DC power transmission systems economical. All of these devices function as rectifiers.

{{As of|2009}} it was expected that these high-power silicon "self-commutating switches", in particular IGBTs and a variant thyristor (related to the GTO) called the [[integrated gate-commutated thyristor]] (IGCT), would be scaled-up in power rating to the point that they would eventually replace simple thyristor-based AC rectification systems for the highest power-transmission DC applications.<ref>{{cite book|first1=Jos|last1=Arrillaga|first2=Yonghe H|last2=Liu|first3=Neville R|last3=Watson|first4=Nicholas J|last4=Murray|title=Self-Commutating Converters for High Power Applications|publisher=John Wiley & Sons|isbn=978-0-470-68212-8|date=12 January 2010}}</ref>