On Fri, 21 Jan 2011 18:09:26 -0800, David Nebenzahl
wrote:

The discussion started with a mention of 2-phase power. Turns out that
in the world of electrical power, this has a specific meaning. It refers
to a now-obsolete system of generating power in 2 phases that were 90°
apart, and was used at Niagara Falls:

http://www.3phasepower.org/2phasesystems.htm

And of course there's 3-phase power, widely used today.

The problem is this: several people, myself included, contend that the
two "legs" of power produced by a center-tapped transformer do, in fact,
constitute two separate phases of power, 180° apart. (This is how
household power is delivered in North America, with a step-down xfmr at
the power pole delivering 240 volts in the form of 120-0-120.)


Well, if you want to be correct, the house power is split phase, and
not two phase. I suppose there is an arguement that it is two phase,
but say that to a power engineer and you'll get the old raised
eyebrows response!