Question

A voltage commutated chopper operating at $1kHz$ delivers constant load current of $10A$. The minimum time (in $\mu s$) for which the main thyristor should be ON is
(Assume $L=2mH$ and $C=1\mu F$)

Answer 1

The capacitor voltage should change from $+V_S$ to $-V_S$.
So it takes $\pi$ radians
$\therefore {\omega }_{0}t=\pi$
$t=\frac{\pi }{{\omega }_0}=\pi \sqrt{LC}$
$=\pi \sqrt{2\times {10}^{-3}\times 1\times {10}^{-6}}$
$=140\mu s$