Hi again Rob,
Just buying a new SCR at the minute Rob, think that has failed - no output from it anyway.
Do you have a schematic of the interface circuit by any chance, so as i can understand it further?
My understading so far has come from an excellent post you made on a similar issue which stated :
"To make your own would be quite a project. I think do-able, but not all that easy to get right. The voltages and energy involved make it tricky. You could follow the same formula as Power-One: There is an IGBT that switches on the diversion load. An SCR takes care of the crowbar circuit. Then there's the usual electronics to derive a stable power supply for internal use, some 293's for voltage comparators, zeners to drive the SCR, driver transistors, lots of capacitors and a handful of MOVs for surge protection. It's not rocket science, but getting it wrong can be dangerous and/or expensive (as in blown inverters)."
Think I would like to try to build this circuit.However, I wouldn't be sure of component specifications - for a max input to such an interface of 400Vac and a max output of 600V DC to the inverter.
Thanks