I’ve been wondering about the capabilities of IGBT and Mosfets in general , I recently had a few problems with an smps and here is what I wonder , for example the IGBT used in the supply has an absolute maximum rating of 600v and 120 amps at room temp, I can’t recall the exact IGBT in question but I have seen this with other ones too so let me just put for example FGH60N60SF or FGY75N60SMD or other devices , now I have seen they blow whne there is a sudden very large load on the secondary of the smps transformer and in other cases , but let’s take the secondary shorted case as our example. My mains voltage is 230v and the socket delivers about 16-20 amps max then the voltage would probably start to sag. So simple maths gives us about 325v DC rectified. It’s a half bridge topology , prior to the switching transistors there are 4x1000uF capacitor bank , now if there manages to be a short at the secondary side the transistors blow up or short out. My question is why is this so since their ratings are so high , 600v max voltage and 100 to 150 amps of collector current , in such case I was hoping for my 5amp mains fuses to simply blow out and the whole thing would settle easily since the secondary current translates back to the primary side but instead the transistor blow. Could it really be that the 4x1000uF cap bank stores enough energy to be capable of giving more than 100 amps of current for a long enough moment to exceed the quite large rating of the transistors , or is this because the rather small to 247 and other devices simply get too hot too fast under such load and fail primarily due to heat?