On Monday, July 30, 2018 at 2:37:58 PM UTC-4, wrote:


If I'm the one who's dumb, why is it that I'm the only one here who
can give you a simple, logical, straightforward definition of N phase
power? I asked, no one could even define it. I gave it to you:


N Phase Power - A power delivery system that uses N related voltage sources,
that are periodic waveforms of the same frequency, differing only in
phase.

Following your logic that you have to analyze a whole system, then we can't
use electrical engineering tools to
analyze the output stage in an audio amplifier unless we know the whole
"system" from end to end. We can't identify phase relationships in a
part of a circuit, without going all the way back to the generator???

And I keep giving you the opportunity to go all the way back to the generator,
asking the simple questions a beginning elec engineering student or
even a high school student might ask a teacher. Questions you won't
answer, step by step, because you get cornered by the truth. I answer
all your questions.


Put two windings on the same shaft at the generator and feed it to the
house over three wires, shared neutral, with a 90 deg phase
difference between the two coils. Would there then be two phases entering
the homeowner;s house?

Yes or no?

Would there still be two phases there if I rotate one generator coil
so that it's 179 deg phase difference instead of 90?

Yes or no?


If it's 180 phase difference, then what? Is that still two phases?


And if that is still two phases, then it's electrically identical to
what's coming into the house from the center tapped transformer.
Electrons and engineering don't care how it was created, only what is
actually there. As I said before, from an engineering perspective,
let's say I have a black box that has five phases coming out of it, at 120,
150, 180, 210, 240. They are electronically synthesized as you would in
a uninterruptable power supply. Do you need to know what drives it
for there to be 6 phases there? Why does it matter if it's powered
by a DC battery, single phase or 3 phase? Is the 180 one not a legitimate
phase, just because it's at 180?

The other poster raised another good point. If there are not two phases
present, then I should be able to take any two receptacles in a house
and parallel them. Fact is you can't, because they are 180 deg out
of PHASE with each other.

They are NOT 180 degrees out of phase, If they were, the line to line
voltage would be zero.

Wow, you really are confused. Two 120 volt AC sources that are 180 deg
out of phase sharing a common neutral produce 240V between them.




You are just looking at the 2 halves of a 240v
sine wave.
Draw a sine wave. look at the center point and you see what I mean.
It is one sine wave, about 168 P/P (120 RMS) and from the center point
each side is the compliment of the other but it is still one sine
wave.
Until you understand that you will remain confused.

I suppose the prof of electrical engineering, who presented to his peers
at a power industry conference is confused too. Funny, he's saying
EXACTLY what I said. And he goes through many pages of analysis of it
as two phases.

"Distribution engineers have treated the standard "singlephase" distribution transformer connection as single phase because from the primary side of the transformer these connections are single phase and in the case of standard rural distribution single phase line to ground. However, with the advent of detailed circuit modeling we are beginning to see distribution modeling and analysis being accomplished past the transformer to the secondary. Which now brings into focus the reality that standard 120/240 secondary systems are not single phase line to ground systems, instead they are three wire systems with two phases and one ground wires. Further, the standard 120/240 secondary is different from the two phase primary system in that the secondary phases are separated by 180 degrees instead of three phases separated by 120 degrees. What all of this means is that analysis software and methods must now deal with an electrical system requiring a different set of algorithms than those used to model and analyze the primary system. This paper will describe the modeling and analysis of the single-phase center tap transformer serving 120 Volt and 240 Volt single-phase loads from a three-wire secondary."



Why is it that if you're so smart and I;m the one confused that you can't
answer the simple questions I posed?



Put two windings on the same shaft at the generator and feed it to the
house over three wires, shared neutral, with a 90 deg phase
difference between the two coils. Would there then be two phases entering
the homeowner;s house?

Yes or no?

Would there still be two phases there if I rotate one generator coil
so that it's 179 deg phase difference instead of 90?

Yes or no?


If it's 180 phase difference, then what? Is that still two phases?

So I run that into a house as 240/120, how many phases now?

If phase is so simple and you understand it, why can't you answer those
questions?


And if that is still two phases, then it's electrically identical to
what's coming into the house from the center tapped transformer.
Electrons and engineering don't care how it was created, only what is
actually there. As I said before, from an engineering perspective,
let's say I have a black box that has five phases coming out of it, at 120,
150, 180, 210, 240. They are electronically synthesized as you would in
a uninterruptable power supply. Do you need to know what power source
it uses? Why does it matter if it's powered
by a DC battery, single phase or 3 phase? Is the 180 one not a legitimate
phase, just because it's at 180?

The other poster raised another good point. If there are not two phases
present, then I should be able to take any two receptacles in a house
and parallel them. Fact is you can't, because they are 180 deg out
of PHASE with each other.






To make the 2 sides of that transformer 180 degrees out of phase you
would need to wind it in the opposite direction and we know it is just
one winding.

That would be two phases just the same as it is two phases by center
tapping the transformer. If we did it with a separate winding, how
would you tell from the house that it was one vs the other? You
can't. Because there are two phases either way.




Your generator scenario also would require that they both be in phase
so the voltage would add or the resulting end to end voltage would be
zero, even though both were putting out 120.

No idea what your talking about now. And again, why can't you answer
the simple questions one at a time? Go back to the step by step generator
example. You claimed you have to analyze a whole system. I gave you
one in that example, so answer the simple questions.


In fact the farther you take 2 windings out of phase, the lower the
line to line voltage will be, hence 208 on regular 120 degree put of
phase 3P wye. (Sq/Rt of 3).

The line to line of a 2 phase from the two 90 degrees out would be
around 168 (120* sq/rt 2)

Anything else irrelevant that you'd like to toss in to try to avoid
answering those simple questions in sequence?