TRIAC

TRIAC

A TRIAC, or TRIode for Alternating Current is an electronic component approximately equivalent to two silicon-controlled rectifiers (SCRs/thyristors) joined in inverse parallel (paralleled but with the polarity reversed) and with their gates connected together. Formal name for a TRIAC is bidirectional triode thyristor. This results in a bidirectional electronic switch which can conduct current in either direction when it is triggered (turned on). It can be triggered by either a positive or a negative voltage being applied to its "gate" electrode (with respect to A1, otherwise known as MT1). Once triggered, the device continues to conduct until the current through it drops below a certain threshold value, such as at the end of a half-cycle of alternating current (AC) mains power. This makes the TRIAC a very convenient switch for AC circuits, allowing the control of very large power flows with milliampere-scale control currents. In addition, applying a trigger pulse at a controllable point in an AC cycle allows one to control the percentage of current that flows through the TRIAC to the load (so-called "phase control").

Low power TRIACs are used in many applications such as light dimmers, speed controls for electric fans and other electric motors, and in the modern computerized control circuits of many household small and major appliances. However, when used with inductive loads such as electric fans, care must be taken to assure that the TRIAC will turn off correctly at the end of each half-cycle of the ac power.

A snubber circuit is often used to assist this turn off. Snubber circuits are also used to prevent premature triggering. For higher-powered, more-demanding loads, two SCRs in inverse parallel may be used instead of one TRIAC. Because each SCR will have an entire half-cycle of reverse polarity voltage applied to it, turn-off of the SCRs is assured, no matter what the character of the load.

ee also

*Diac

*Silicon-controlled rectifier
*Alternistor

External links

* [http://www.du.edu/~etuttle/electron/elect5.htm A site about thyristors]


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • Triac — Triodo para Corriente Alterna Algunos ejemplos de TRIACs. Tipo Semiconductor Símbolo electrónico …   Wikipedia Español

  • Triac — ist eine englische Abkürzung für Triode for Alternating Current. Auf deutsch sind auch die Begriffe Zweirichtungs Thyristortriode oder Symistor zu finden. Es handelt sich um ein elektronisches Bauteil mit Halbleiterschichtstruktur, das vom… …   Deutsch Wikipedia

  • triac — TRIÁC, triace, s.n. (electron.) Dispozitiv semiconductor care permite circulaţia curentului electric în ambele sensuri. – Din engl. triac. Trimis de dante, 01.07.2004. Sursa: DEX 98  triác s. n., pl. triáce Trimis de siveco, 10.08.2004. Sursa:… …   Dicționar Român

  • Triac — means:* TRIAC or TRIode for Alternating Current. * Triac (car) Green vehicle * Tiratricol Common thyroid hormone analogue used for treating thyroid hormone resistance syndrome …   Wikipedia

  • triac — ● triac nom masculin (anglais triac, de alternative current) Composant électronique bidirectionnel à une seule électrode de commande …   Encyclopédie Universelle

  • Triac —   [Kurzwort aus englisch triode alternating current switch »Trioden Wechselstromschalter«] der, (s)/ s, Zweirichtungs Thyrịstortriode, Halbleiterbauelement mit einer Schichtenstruktur, aus der sich eine Funktion wie bei zwei …   Universal-Lexikon

  • triac — ☆ triac [trī′ak΄ ] n. [tri(ode) a(lternating )c(urrent switch)] Electronics a type of thyristor that functions as an electrically controlled switch for alternating current …   English World dictionary

  • Triac — Pour les articles homonymes, voir Triac (homonymie). Symbole électronique du triac Le triac est un composant électronique équivalent à la mise en parallèle de deux thyristors montés t …   Wikipédia en Français

  • Triac — Un Triac es un dispositivo semiconductor, de la familia de los tiristores . La diferencia con un tiristor convencional es que éste es unidireccional y el triac es bidireccional. De forma coloquial podría decirse que el triac es un interruptor… …   Enciclopedia Universal

  • triac — simetrinis trinistorius statusas T sritis radioelektronika atitikmenys: angl. bidirectional triode thyristor vok. Doppelwegthyristor, m rus. симистор, m; симметричный триодный тиристор, m; триак, m pranc. thyristor triode bidirectionnel, f; triac …   Radioelektronikos terminų žodynas

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”