And that datasheet is the opposite from how I'd expect the labelling to be, but the fact they include a schematic removes the doubt.I've just found this via Schneider so when i go back to replace the main supply cable i will alter the transformer to be on +15v.
Output voltage was negligible it's only a control circuit with no lamps etc anyway.
The equipment did have a 400v Primary to 115v & 20v secondary transformer.
Price from OEM, $1015.
The 20v powers a motor protection board which monitors two thermistors in the motor.
Since a aftermarket motor overload has been fitted, i've disconnected the motor protection board.
What i'm hoping is the motor protection board will run from a small separate transformer possibly 400v to 24v.
Although the 24v may upset the board or the thermistor temperature resistance.
View attachment 403789
20VAC does seem to be a random voltage, but if it's being rectified/regulated to 24VDC, it'll give ~28VDC after rectification, so only means the regulator has to drop 4V.
Pushing that to 24VAC is going give ~34VDC, which may be more than the regulator can handle.
A little bit reverse engineering of the motor protection board might give a clearer idea of what will work.