Branch : Computer Science and Engineering
Subject : Fundamental of Electronic Devices
Unit : Basic Electronics
TRIAC
Introduction:
It is a three terminal device.Funtionally equivalent to two SCRs connected antiparallel.
Basic Structure:
- In figure given below MT1 is the Main Terminal 1 and MT2 is the Main terminal 2.
- Switching control terminals are the gate and MT1 irrespective of the direction of current to be switched.
- TRIAC has a complicated structure
- Bidirectional device
- It Can be triggered when MT2 i s ve w.r.t. MT1 & ve IG w.r.t. to MT1
- It Can also be triggered when MT2 is –ve w.r.t. MT1 & -ve IG w.r.t. to MT1
I-V Characterstics:
- The breakover voltage of the Triac can be controlled by the application of a positive or negative signal to the gate.
- As the magnitude of the gate signal increases, the breakover voltage decreases.
- Once the Triac is in the ON state, the gate signal can be removed and the Triac will remain ON until the main current falls below the holding current (IH) value.