Characteristics: Triac - nptel

1.
i. Forward break down voltage reduces with increasing gate current. It increases with
junction temperature up to certain value of the junction temperature and then falls rapidly
with any further increase in temperature.
Reverse break down voltage is independent of the gate current magnitude but decreases
with increasing junction temperature.
ii. Forward leakage current is independent of the gate current magnitude but increases with
junction temperature.
Reverse leakage current increases with both the junction temperature and the magnitude
of the gate current.
THM
200V
200V
-
+
C
THA
20 A
2. Figure shows the equivalent gate drive circuit of the thyristor. For this circuit one can write
E = R i + V OR V = E - R i
g g g g
The diode D clamps the gate voltage to zero when E goes negative.
Now for i g = O, V g = E. Since V
g Max= 10 v E = 10 v
N2 N2
15
But E = 15 ∴ = = 1.5
N N 10
1 1
Gate pulse width = 0.4 × 10 -4 Sec = 40μs.