TRIAC Study Materials


TRIAC Study Materials

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 TRIAC is a three terminal semiconductor switching device. They are MT1, MT2 and gate. Here, the gate terminal is used to control the ACin a load. TRIAC is a short version of TRIODE AC switch. The flow of current in TRIAC is bi-directional that means current can flow in both directions.


The structure and symbol of TRIAC is shown in the Figure . It comprises of two SCRs connected in the anti-parallel direction. It acts as a switch for both the directions. From the diagram we can understand that the MT1and gate terminals are close to each other. The gate provides control over conduction in either direction.

Application of TRIAC

  1. It can be used as a static switch to turn AC power ON and OFF.
  2. It is used for motor speed control.
  3. It is used for illumination control.
  4. It is used for heater control.
  5. It is used for phase control.

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