A triac is an alternating current triode, a semiconductor device that is designed to work with alternating current. It is useful where bipolar and field transistors cannot be used because they in turn cannot work with alternating current. The exception is when we separate the positive part of the cycle from the negative part and use a separate transistor for each of them. However, we can avoid this with the use of triacs. So we can consider that the triac is a kind of transistor. It is used in power and power control systems in AC devices. It can be placed in an electric heater for example. Individual triacs are different from each other, which allows to precisely adjust them to the specifics of the equipment and conditions in which it works. Moreover, triacs are available in our store as single products, as well as in sets consisting of several elements, triacs of the same size and parameters.
Triacs are also a triode and belong to the group of transistors. Their characteristic feature is the ability to conduct current in both directions, in the case of a thyristor it is impossible, because in it the current flows only in one direction. Moreover, unlike the thyristor, most triacs can be triggered by applying both positive and negative voltage to the gateway. For thyristors it is always positive voltage. Regardless of the application, both elements will react in the same way, they will remain open regardless of whether the gate current stops or not. It is important that the current flows through the system at a level not lower than the holding current. This whole process is called triac control.
The construction of the triac is based on four layers of PNPN semiconductors. Current outlets are the extreme layers that create current outlets. These are the anodes, which create appropriate conditions for the flow of current between them. Internal layers have control leads, so they are the so-called base. The conduction between the anodes is initiated when a positive or negative voltage is applied to the base. The current will still flow between the triac anodes when the base voltage is switched off. It will be triggered only when the voltage between the anodes drops below a certain threshold, i.e. the already mentioned holding current.
Triacs can perform several functions in devices and electronic circuits. Most often they are bi-directional switches in alternating current circuits. At the same time, they can be used as relays as well as DC power regulators. The application is due to bi-directional triacs. Using them at a controlled alternating current phase angle in a circuit allows for very good and effective control of the average current that flows into the load. Such operation and properties allow to use triacs for speed-controlled AC motor. They are used, among other things, to control electrical devices such as electric heaters, as well as dimmers, which are elements of intelligent lighting.
Technical parameters of the triacs determine the scope of their use, as well as the way and efficiency of work. Their advanced models, characterized by improved shutdown parameters are called alternistors. They are used at particularly high surges, which ordinary triacs may not cope well with. This solution allows the implementation of even more extensive projects, with more freedom to adjust the technical parameters with a guarantee of effective cooperation between the individual elements.
Check out the offer of the Botland store, where we have gathered many different triacs, differing primarily in key parameters. They are available as single products, as well as in practical sets consisting of several triacs.