Question

The waveform shown below represents the voltage across the switch and current through the switch. The energy loss occurring during turn-on process in the switch is

• A. 6.5 mJ
• B. 2.5 mJ
• C. 5.75 mJ
• D. 7.00 mJ

Answer 1

The correct option is D 7.00 mJ

Total energy loss, $E_{total}=E_{t1}+E_{t2}$

$E_{t_1}={\int }_0^{t_1}V.i.dt$

As voltage across the switch is constant i.e. 500 V

$=500{\int }_0^{t_1}i.dt=500\times \frac{1}{2}\times (0.4\times {10}^{-6})\times 40=4mJ$

Similarity $E_{t_2}={\int }_0^{t_2}Vi.dt$

As switch current is constant i.e. 30A

$E_{t_2}=30{\int }_0^{t_2}V.dt=30\times \frac{1}{2}\times (0.4\times {10}^{-6})\times 500=3mJ$

$\therefore$ Total energy loss in process

= 4 mJ + 3 mJ = 7 mJ