It is an autosynchronizer. I would not even consider using it for anything other than a toy or museum piece. It was a troublesome device even when new about 40 years ago. There are much better devices available now.
dpc is correct that there are better, cheaper ones available now, but there are still a lot of XASV's reliably in service. Eaton/Cuttler Hammer bought Westinghouse's swgr line years ago and should be able to furnish the inst. man. If you strike out with them we can find you one next week.
It is a rack containing a power supply and several circuit boards. Each circuit board has a specific function such as voltage matching, speed matching, voltage acceptor, and synchronizing. I see only the schematics made it in the upload. I will also upload the instruction leaflet.