The $$SCR$$ in the circuit shown has a latching current of $$40$$ $$mA.$$ A gate pulse of $$50$$ $$\mu s$$ is applied to the $$SCR$$. The maximum value of $$R$$ in $$\Omega $$ to ensure successful firing of the $$SCR$$ is ____________.

Thyristor $$T$$ in the figure below is initially off and is triggered with a single pulse of width $$10\mu s.$$ It is given that $$L = \left( {{{100} \over \pi }} \right)\mu H$$ and $$C = \left( {{{100} \over \pi }} \right)\mu F.$$ Assuming latching and holding currents of the thyristor are both zero and the initial charge on $$C$$ is zero, $$T$$ conducts for

Match the switch arrangements on the top row to be steady $$-$$ state $$V$$ - $$I$$ characteristics on the lower row. The steady state operating points are shown by large black dots.

A $$1:1$$ pulse transformer $$(PT)$$ is used to trigger the $$SCR$$ in the adjacent figure. The $$SCR$$ is rated at $$1.5$$ $$kV$$, $$250$$ $$A$$ with $${{\rm I}_L} = 250\,mA,\,\,{{\rm I}_H} = 150\,mA,$$ and $${{\rm I}_{G\max }} = 150mA$$ with $${{\rm I}_L} = 250\,mA,$$ $${{\rm I}_{G\min }} = 100mA.$$ The $$SCR$$ is connected to an inductive load, where $$L$$ $$=150$$ $$mH$$ in series with a small resistance and the supply voltage is $$200$$ $$V$$ $$dc.$$ The forward drops of all transistors/diodes and gate $$-$$ cathode junction during $$ON$$ state are $$1.0V$$

The minimum approximate volt $$-$$second rating of the pulse transformer suitable for triggering the $$SCR$$ should be: (Volt - second rating is the maximum of product of the voltage and the width of the pulse that may be applied)