Well, thanks! It was worth a try. I'll leave the frequency at 60Hz with a comment that it could be wrong.
Trumpy,
you could be right on the right one.
The transformer looks like the ones in Sweden, which are of course usually made by ABB. But, then again, I don't know what transformers look like in other countries.
Belgian,
Thanks for your input. I know that you have 20A circuits, but can you connect a 20A appliance to a socket? I was under the impression that the French/Belgian socket was rated for 16A. Or are special 20A sockets common? I'm happy to correct the information if I'm wrong.