Question

A thyristor switching circuit is shown below. The thyristor is rated for a latching current of 5 mA and is turned on within 5$\mu s$. The value of inductance L to be designed can be

• A. 0.062 H
• B. 6 H
• C. 0.601 H
• D. 0.104 H

Answer 1

The correct option is A 0.062 H

For proper turn on

$I_A\ge I_L$

$I_A=\frac{1}{L}\int Vdt+\frac{V}{R}$

$I_A=\frac{V}{L}t+\frac{V}{R}$

or $\frac{V}{L}t+\frac{V}{R}\ge 5\times {10}^{-3}$

or $\frac{50}{L}\times 5\times {10}^{-6}+\frac{50}{50\times {10}^3}\ge 5\times {10}^{-3}$

or $\frac{250\times {10}^{-6}}{L}\ge 4\times {10}^{-3}$

Or $L\le \frac{250\times {10}^{-6}}{4\times {10}^{-3}}$

or $L\le 0.0625H$

Hence, L = 0.0625 H.