This may be way off the mark, but corner-grounded 3ø4W∆ doesn't sound right. If one coil center tap is not grounded, then one 120V winding is properly grounded, but the other 120V winding is 120V to ground on one side, and the other is 240V to ground. That could make for a deadly screwshell in a 120V lampholder. That seems to go against a lot of electrical custom in the US, particularly when the mid-coil ground would provide two grounded 120V connections.
There might be some old systems found that way, but to do it intentionally doesn't seem likely. There would be no point or advantage to such an arrangement, and it would take a more complex metering arrangement to measure power flow.
[This message has been edited by Bjarney (edited 06-08-2002).]
