On Sat, 3 Jan 2004 10:34:35 -0500, "BFoelsch"
wrote:


My absolute favorite was the 6 phase double delta. Picture a straight 220
(YES, 220, not 240) delta connection. Now, center tap all the transformers,
and these midpoints give you another delta at 110 for the lighting load. Of
course, the whole thing is ungrounded. Yes, all the light switches in the
building were 2 pole. Yes, the small motors were 110 volt 3 phase. This
system gives you 2 three-phase voltages out of one set of transformers, The
power factor transforms at unity, unlike many connections. Only thing is, it
is very had to protect the transformers unless you use 6 primary fuses.


Wow. If it was delta, then 110 3-phase would require 6 wires (or five
if you cheat and share one corner) so the 110 3-phase motor would need
three isolated windings and most likely a 6-pole on/off switch. Was it
really like that? Might it have been wired wye with one central
common/neutral? That seems more logical, but then maybe it wasn't very
logical.

Years ago, maintenance electricians had to be aware of a lot of varied
systems. Today, life is a whole lot simpler.

The thing that always amazes me is that buildings are wired in the
most bizarre ways, and no documentation is left behind. If you call in
an electrician, they figure it out somehow, kluge it some more, and
leave.

John