Editing Ignitron (section)

==Applications==
Ignitrons were long used as high-current rectifiers in major industrial and utility installations where thousands of amperes of [[alternating current|AC]] must be converted to [[direct current|DC]], such as [[aluminum]] smelters. Ignitrons were used to control the current in electric [[welding]] machines.  Large [[electric motor]]s were also controlled by ignitrons used in gated{{clarify|date=June 2013}} fashion, in a manner similar to modern semiconductor devices such as [[silicon controlled rectifier]]s and [[TRIAC|triac]]s. Many electric [[locomotive]]s used them in conjunction with [[transformer]]s to convert high voltage AC from the [[overhead lines]] to relatively low voltage DC for the [[traction motors]]. The Pennsylvania Railroad's [[PRR_E44|E44]] freight locomotives carried on-board ignitrons, as did the Russian [[:ru:ВЛ60|ВЛ-60]] freight locomotive. For many modern applications, ignitrons have been replaced by solid state alternatives.

Because they are far more resistant to damage due to [[overcurrent]] or back-voltage, ignitrons are still manufactured and used in preference to semiconductors in some installations. For example, specially constructed "pulse rated" ignitrons are still used in certain [[pulsed power]] applications. These devices can switch hundreds of kiloamperes and hold off as much as 50&nbsp;kV. The anodes in these devices are often fabricated from a refractory metal, usually [[molybdenum]], to handle reverse current during [[ringing (signal)|ringing]] (or oscillatory) discharges without damage. Pulse rated ignitrons usually operate at very low [[duty cycle]]s. They are often used to switch high energy [[capacitor]] banks during [[electromagnetic forming]], [[electrohydraulic forming]], or for emergency short-circuiting of high voltage power sources ([[Crowbar (circuit)|"crowbar"]] switching).
[[File:Philips ignitron pl5551a.jpg |thumb|right| An ignitron rated 56 amperes. Cooling jacket connections visible. In use the device was mounted so that the text would be upright. ]]