David Nebenzahl wrote:

On 1/23/2011 4:44 PM Wild_Bill spake thus:

These comments are logical and correct representations of the power
system that most of us use. For single phase motors, a 120VAC motor is
a single-phase motor, just as a 240VAC motor is referred to as a
single-phase motor, not a 2-phase motor because it's using 2 hot lines.

This issue is one that just gets argued endlessly by amateurs and
intellects to no end.. essentially a waste of useful time on an issue
that's widely misunderstood for all the wrong reasons.


I disagree entirely. Yes, in this case it's a semantic debate--what I
contend is actually 2-phase power (120-0-120 derived from a
center-tapped transformer) is not *called* that by the electric power
industry. It is, nonetheless, truly two phase power.

I think it's important because the idea of phases in electrical power is
an important one, even to a simpleton like the average electrician,
never mind the EE.

Example: if you're going to wire an Edison circuit (where two hots from
different phases, meaning different sides of the distribution panel, are
wired with a common neutral), you ought to understand electrical phases,
especially the consequences of two phases 180° apart. After all, that's
how the currents from the two sides cancel each other. Failure to grasp
such principles can, and do, lead to real-world consequences like
building fires.

Pick the issue apart just for sport, if you like, but the majority of
domestic power supplies are single-phase.. period.


Look anywhere you can for a New 2-phase motor.


Who said anything about a 2-phase motor? Nobody, so far as I can tell.

I'm saying that the ENTIRE DOMESTIC POWER SUPPLY FROM THE SECONDARY OF
THE POWER COMPANY'S TRANFORMER is 2-phase. Once you plug in a 120 volt
anything, or even many 240 volt anythings, you're only using one phase.
Sheesh.

The only individuals that would be describing a new motor as a 2-phase
motor will be some misguided trainee or someone taking advantage of
your stupidity of asking for one.


Again, where did this straw man come from?

Please notice that because of your non-standard top posting, any
previous replies have been cut off. Please do what 99% of others do here
and bottom post.



Don't waste your breath. it's not worth the effort.

Knowing that you understand it should be enough..

And by the way, I was looking at a 3 wire motor today, 2 phases of 180
apart with CT to operate it (3 wire motor). It was attached to a gear
box and only ran one direction, but you could use it as a stepper
(servo) or full out run. Most likely some custom motor for an application.

Jamie