Quote Originally Posted by Chan Tran View Post
You can get this one which is not exactly cheap but reasonable in price.
http://www.automationdirect.com/adc/.../PSM24-REM360S
That's pretty much exactly the sort of thing I was considering, except more the brick form-factor than DIN-rail.

In terms of my current transformer, it could well be a ferroresonant as it has two separate secondaries and I think there's a big capacitor in there. Ferroresonance didn't occur to me at the time (I had it open to trace the schematic for the back plug) so now I'm going to have to check.

adelorenzo: they are transformers. They give you isolation from the main supply and step the voltage down from 115 or 240V to (probably) 24V. They may or may not be ferroresonant. You must use them for their voltage-converting role if nothing else.

silveror0: shouldn't matter for regulation purposes. If it's always on (timer after stabiliser) it will use more power, but that's not an uncommon arrangement.