On 1/22/2011 7:07 PM, David Nebenzahl wrote:
On 1/22/2011 4:45 PM Jeffrey Angus spake thus:

Power distribution being what it is, the 240/120 transformer on the
pole is sourced with _ONE_ phase of the 3-phase feed for the area.
That there is a center tap allowing for 120/120 or 240 loads is
immaterial. It's STILL single phase.

Keep in mind the premise of my original question. Remember I pointed out
that 120-0-120 current supplied by a center-tapped transformer is *not*
called "2-phase" by those in the electrical power industry, but that it
is, in fact, 2-phase power. Do you disagree that there are actually two
separate phases of power present at the secondary of the transformer?

Regardless of what they call it ...



Nope, single phase.

The definition of "more than one" phase is a difference
of something other than 0 or 180 degrees.

With either 2-Phase (the old 90 degree system) or 3-phase
(current 120 degree system) the phases can NOT be generated
with a simple transformer. They are generated by multiple
alternators mounted on a common shaft.

With a single transformer, and a center tap, you have two
voltages, in phase, that add together.

It's single phase.

Jeff