What are the triggering modes of TRIAC?

There are the triggering modes of TRIAC (Triode for alternating current) are given below.

• I ⁺mode: The ‘I’ indicates first quadrant operation. The MT₂ (main terminal 2) positive with respect to MT₁ (main terminal 1). The ‘+’ symbol shows the polarity of gate (G) with respect to MT₁ (main terminal 1). In this mode the conduction of current takes place from MT₂ to MT₁.

• I ^–mode: The ‘-’ shows the polarity of gate (G) with respect to MT₁ (main terminal 1). The conduction of current takes place from MT₂ to MT₁.

• III ⁺mode: The ‘III’ indicates the third quadrant operation where MT₁ (main terminal 1) is positive with respect to MT₂ (main terminal 2). The ‘+’ symbol shows the polarity of gate with respect to MT₁ (main terminal 1). The conduction of current takes place from MT₁ to MT₂.

• III ^–mode: The ‘-’ symbol shows the polarity of gate (G) with respect to MT₁ (main terminal 1). The conduction of current takes place from MT₁ to MT_1­.