I'm looking for a way to step down 3 phase, 2kV AC power to 3-12V DC. I do not have a neutral, just the 3 phases and ground. This will be entirely isolated, nobody will be anywhere near this thing. In fact, it will placed inside a thick, grounded metal case that will be essentially tamper-proof.
The components need to be rated for a 175C environment... which really messes with the available options.
I'd also like it to be able to survive and hopefully still operate if one of the phases is shorted out or grounded. :) So... kinda harsh criteria and environment.
On the plus side, the thermal sinking capability of the system is quite high.... but then I'd prefer to minimize that as much as possible. It's there if required.
I don't need that much, somewhere between 5-20mA (probably around 10mA).
I'm currently rectifying the three phases with half-bridges, voltage dividing that (burning power in the process, but limiting voltage on the smoothing cap). It seems to work, but I'm sure there's a better way.
I've looked a little into custom transformers, but it's not clear how much power will be wasted in those either.
EDIT This can weight a good bit (< 50 lbs, target is maybe 10-20ish). It should fit in say a 4" x 12" cylinder, although preferably under 8" long.
Thoughts would be appreciated.