Very interesting video - the shattering of the case of the circuit breaker shows the significance of not exceeding the 10KA or 6kA breaking rating - and actually it is surprising to me that the really high current failure mode mode is not the arc-traps, but the magnetic convulsion of the actuating solenoid. The fact the fault is short duration DC rather than part of an AC cycle is probably not that significant.
given that machine has a maximum output of 220uF at 5000V, we can estimate an upper limit on the total energy available as 2.7 k joules, but I'm not sure what R to assume to deduce an I2 t equivalent. I suspect a fuse might have fared better.
It is a shame he cannot capture the current waveforms, to measure very fast pulse discharge currents in circuits like that normally involves cascaded current transformers . As an example of why, two transformers each transforming say 50:1 can be made to have a much faster response, due to the lower inductance and inter-winding capcacitance, than one coil of say 2500:1 ratio. Then there is a need to wind the multi turn windings in thin coax to avoid electrostatic coupling if dv/dt is very high, and to be careful with the termination impedances to avoid line reflections.
"Ooops" Even somebody as 'experienced' with an electrical understanding was unable to predict the ferocity of the explosion. He seemed quite apologetic. So boys and girls don't play around with electricity !
