Question

In the circuit shown below, if the maximum permissible current through the main SCR $T_M$ is 2.5 times the load current, the value of the commutating component L in $\mu$H is_____

Answer 1

Peak current through the main thyristor $T_m$ is

$i_p=\frac{V_s}{R}+V_s\sqrt{\frac{C}{L}}$
$2.5\frac{V_s}{R}=\frac{V_s}{R}+V_s\sqrt{\frac{C}{L}}$

$1.5=R\sqrt{\frac{C}{L}}$
$L=\frac{R^{2}C}{{1.5}^2}$
$L=\frac{100\times 14.43\times {10}^{-6}}{{1.5}^2}$
$=641.33\times {10}^{-6}$ H
$=641.33\mu$H