Caution is the key to success in power converters

I work across the scale of power electronics in voltages and currents. From switchers of 1W for powering ICs to 3kW telco power supplies up to multi-megawatt power converters for reactive power control in AC transmission networks and into power converters for high voltage transmission.

There is a difference in how you can work on these different scale converters. This difference is down to how much the prototype you are destroying costs, how long it takes to rebuild it and how easily it will kill you. When you spend more than 2 million on the prototype parts then you do not ever blow it up. If the high voltage on your converter is 15kV or more then there is no way to probe it with an oscilloscope directly and no possibility to be anywhere near that voltage without being hurt. So the level of care at these bigger power levels is higher and the consequence of a mistake is so high that the process needs to be much more detailed and controlled mostly for safety's sake. We find that our big power converter processes really help when working on smaller converters. The processes include sign offs for safety, designed and prescribed safety and earthing systems for each converter, no scope probes put on and off live parts and working in pairs at all times with agreed planned actions. Pair working is one thing that may save you in the event of an electric shock. These processes seem very slow and cumbersome to engineers who work on low voltage (<1000V) but they are very useful even at low voltage.

Having said all that, experienced cautious engineers prevent converter blow ups. Add just a little bit of process and success can go up significantly. I think that an analysis of Dr Ridley's failure list will point to actions that will improve success.

As my boss at one of those really large converter companies used to say "Stamp out converter fires".