Ignitron

Ignitron

An ignitron is a type of controlled rectifier dating from the 1930s. Invented by Joseph Slepian while employed by Westinghouse, Westinghouse was the original manufacturer and owned trademark rights to the name "Ignitron".

It is usually a large steel container with a pool of mercury in the bottom that acts as a cathode during operation. A large graphite or refractory metal cylinder, held above the pool by an insulated electrical connection, serves as the anode. An igniting electrode (called the "ignitor") is briefly pulsed with a high current to create a puff of electrically conductive mercury plasma. The plasma rapidly bridges the space between the mercury pool and the anode, permitting heavy conduction between the main electrodes. At the surface of the mercury, heating by the resulting arc liberates large numbers of electrons which help to maintain the mercury arc. The mercury surface thus serves as the cathode, and current is normally only in one direction. Once ignited, an ignitron will continue to pass current until either the current is externally interrupted or the voltage applied between cathode and anode is reversed.

Ignitrons were long used as high-current rectifiers in major industrial and utility installations where thousands of amperes of AC current must be converted to DC, such as aluminum smelters. Large electric motors were also controlled by ignitrons used in gated fashion, in a manner similar to modern semiconductor devices such as silicon controlled rectifiers and triacs. Many electric locomotives used them in conjunction with transformers to convert high voltage AC from the catenary to relatively low voltage DC for the traction motors. For most of these applications, ignitrons have been replaced by solid state alternatives.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 50,000 volts. The anodes in these devices are often fabricated from a refractory metal, usually molybdenum, to handle reverse current during ringing (or oscillatory) discharges without damage. Pulse rated ignitrons usually operate at very low duty cycles. 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" switching).

References

* [http://mdk2001.web.cern.ch/mdk2001/Proceedings/Session13/welleman.PDF Semiconductor switches replace thyratron and ignitrons]

ee also

* Thyratron
* Thyristor
* Krytron
* Triggered spark gap
* Pulsed power
* Mercury arc valve


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  • ignitron — IGNITRÓN, ignitroane, s.n. (elt.) Tub redresor cu un singur anod, cu descărcare în vapori de mercur şi cu un electrod auxiliar de aprindere; excitron. – Din engl., fr. ignitron. Trimis de gall, 13.09.2007. Sursa: DEX 98  IGNITRÓN s.… …   Dicționar Român

  • ignitron — ● ignitron nom masculin (anglais ignitron, de électron) Tube redresseur à gaz, dont la cathode est constituée par du mercure liquide et dans lequel l amorçage est renouvelé à chaque période grâce à une électrode spéciale. ignitron n. m. ELECTRON… …   Encyclopédie Universelle

  • ignitron — [ig nī′trän΄] n. [ IGNI(TE) + (ELEC)TRON] a type of mercury arc rectifier tube having a mercury pool cathode and a single graphite anode: when a current is passed through an igniter rod into the pool, the mercury vapor is ionized and an arc… …   English World dictionary

  • Ignitron — (1) Anode, (2) Kathode, (3) Zündelektrode (Ignitor), (4) Quecksilbersee, (5) Keramischer Isolator, (6) Kühlflüssigkeit …   Deutsch Wikipedia

  • ignitron — /ig nuy tron, ig ni tron/, n. Electronics. a cathode arc vacuum tube with an auxiliary electrode projecting into a pool of mercury: it conducts current when the anode is positive. [1930 35; IGNI(TER) + TRON] * * * ▪ electronics        electron… …   Universalium

  • Ignitrón — (1) Anodo, (2) Cátodo, (3) Ignitor, (4) Mercurio, (5) Aislante cerámico, (6) Fluido refrigerante. Un ignitrón es un tipo de rectificador controlado que data de la década de 1930. Fue inventado por Joseph Slepian mientras trabajaba para… …   Wikipedia Español

  • Ignitron — ignitronas statusas T sritis fizika atitikmenys: angl. ignitron vok. Ignitron, n rus. игнитрон, m pranc. ignitron, m …   Fizikos terminų žodynas

  • ignitron — ignitronas statusas T sritis fizika atitikmenys: angl. ignitron vok. Ignitron, n rus. игнитрон, m pranc. ignitron, m …   Fizikos terminų žodynas

  • Ignitron — (1) Anode, (2) Cathode, (3) Igniter, (4) Mercure, (5) Isolateur céramique, (6) Fluide de réfrigération Un ignitron est un dispositif électronique utilisé pour redresser le courant alternatif. Il a été inventé en 1930 par Joseph Slepian  …   Wikipédia en Français

  • Ignitron — Ịg|ni|tron auch: Ịg|nit|ron 〈n. 11; Phys.〉 Gasentladungsröhre mit einer über eine Hilfselektrode steuerbaren Zündung mit ähnlichen Eigenschaften wie ein Relais, wird zur Steuerung hoher Ströme u. Leistungen eingesetzt [zu lat. ignis „Feuer“] *… …   Universal-Lexikon

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