I think it has to do with a communication system in a small town I an traveling to. The public works dept secretary said it would be nice if the engineer was familiar with "ATS systems". I did not have time to press for more info.
I'm with EEJaime--could be Automatic Throwover Switch (pretty much synonymous with the Transfer). Basically a device switching from one power source to another (automatically) like a redundant power feed or UPS. Might want to bring an electrical engineer on the trip .
.