Thanks! You input on both this topic and the other is appreciated.
Yes, the idea is that this should act just like a zig-zag-transformer.
The reason is too save on copper. If you can't balance the loads very well on a three wire system, you'd have a voltage drop in the neutral. This would be avoided by this setup, but of course you'd instead get a voltage drop across the autotransformer. But this should be less than it would have been in a real neutral conductor. That is, I think so.
This of course depends on the transformer and the size of the wires.
Yes, the potential of the neutral will shift. But it does so on an ordinary three wire system as well because of the voltage drop in the conductors. But you could be right in that the effect will be more severe in this case and therefore cause problems.
If you leave the "fake" neutrals floating with respect to ground and treat them as live conductors, does that solve the problem? It leaves you with some problems when it comes to equipment ground, but I think it is manageable.
If this is such a great idea, why haven't one heard of it? There must be a catch somewhere. There isn't room for a 19th century innovation in the 21th century.