Hullo.
I was asked this question during my Lab viva.
" There is a circuit with SCR, without the gating circuit of the SCR connected ( Assume it to be isolated so that the firing of the SCR wont occur anyway due to it. ) The present Voltage source (V1) is a
100V rms sine supply. Presently, the SCR doesnt condect, i.e the SCR is OFF. The V1 is disconnected, another Voltage source (V2), 100 V rms, sine o/p is connected. The SCR now conducts !!! How ??? "The answers given by me were
- The new Vsource must have given a step i/p and hence the Voltage breakdown ( dv/dt) of the SCR must have occured. ( He shook his head, as in NO )
- The temperature must have changed during the process of changin of Vsource. ( Again shook his head.)
- The internal resistance of the V2 must be less so that it gives somewht higher o/p to cause breakdown of SCR.. ( Again the wrong answer he said. )
So, WHat else can it be ?????