[bigger_cheese]

Output on control system HMI Scada screens for stuff like Tilt Drives are all in degrees as well, in this respect it's like the Kelvin scale. Control system doesn't display thermocouple readings in Kelvin either (at plant I work at Temperature setpoints are displayed as degree Celsius).

You might use Radians/Kelvin internally for ease of calculation but they aren't numbers you quote around or report things in.

[anyfoo]

I would be very surprised though if the people who actually implement the control systems (as in doing the hard math) don't use radians, though. Is that really not the case? Using degrees just seems like unnecessary extra steps when dealing with transfer functions...

[bigger_cheese]

Internally yes they probably convert but it is not exposed anywhere, kind of like Chemical reaction you convert everything to Mols internally to do the calculations but externally you report all of the inputs as a mass.

The control system won't tell the operator to add an extra 0.3 mols of reactant or to tilt the furnace by Pi/4 radians

[anyfoo]

Yeah, I meant the people who build the control system platform, not their operators!