These would be two digit alpha codes used in fossil and nuke plants.
Just off the top of my head:
SJ: Feedwater system
EC: Low voltage power system
sorry, I'm at home and can't come up with any others at the moment...
I'm not sure of the logic to them, but we have a document labeled ANSI/IEEE Std 806 - 1986 with a ton of existing codes listed. Our CMMS uses them in the asset number and I'd like to use something standard for the wind turbines rather than creating something off the top of my head.
Any help would be appreciated.