TRIAC

What is TRIAC?

In industrial electronics, a TRIAC (Triode for Alternating Current) is a type of semiconductor device used to control the flow of alternating current (AC) in a circuit. It is essentially a bidirectional version of the more common silicon-controlled rectifier (SCR). The TRIAC can conduct current in both directions, making it suitable for controlling AC power.

Construction & Symbol of TRIAC

A TRIAC consists of two thyristors in antiparallel. It can control alternating current. These thyristors are arranged in such a way that they can be triggered to conduct current during both halves of the AC waveform. A TRIAC has three terminals MT1, MT2, and Gate.

Working Principle of TRIAC

With no gate current, the triac is in off condition. It can be turned ON by increasing the supply voltage equal to the breakover voltage.

But practically, it is not done in this way. The triac is turned ON by applying the proper gate voltage signal. By passing a proper gate current at the gate, the triac will conduct whether terminal MT2 is positive or negative w.r.t. MT1.

If MT2 is positive with respect to main terminal no 1 (MT1), then the current will flow from MT2 to MT1.

If MT2 is negative with respect to MT1, then the current will flow from MT1 to MT2.

V-I Characteristics of TRIAC

The V-I (Voltage-Current) characteristics of a TRIAC represent how the device behaves in terms of current conduction in response to varying voltages applied to its terminals. A TRIAC is a bidirectional semiconductor device used for controlling AC power, and its V-I characteristics exhibit different modes of operation based on voltage and current conditions. Below shows the graph demonstration of TRIAC.

Applications of TRIAC

• Used in Light dimming circuit.
• Used in Heater Control Circuit.
• Also used in Motor Driver Circuit.

Read More

• What is DIAC? About construction and Working Principle.
• Silicon Controlled Rectifier.
• Power Diode and Power Transistor.
• MOV and Snubber.