On Mon, 30 Jul 2018 13:06:50 -0700 (PDT), trader_4
wrote:

On Monday, July 30, 2018 at 3:29:07 PM UTC-4, Single Phase wrote:
On 7/30/2018 12:56 PM, tarder_4 wrote:
If it's 180 phase difference, then what? Is that still two phases?

Just to be clear, this argument started after someone referred to single phase service as 2-phase service.Â* If you call the power company and ask to have 180° 2-phase electric service installed, they'll tell you they only offer single and three
phase...though there might be some 90° 2-phase installations still in operation. Furthermore, if you connect a dual trace scope up a certain way, it will look like you have two phases.Â* While that's a nice parlor trick that might make a slow student
scratch their head, the truth is that there is only one phase on the transformer secondary.


It's not a parlor trick. Are you going to tell this power industry engineer,
an electrical engineer with 40 years experience, a Life Fellow of the IEEE,
who presented the
below paper at an industry conference of his peers, that he's wrong too?
I don't see either you or Fretwell addressing it. He addresses exactly what we're talking about
and says that 240/120 HAS TO BE ANALYZED AS A TWO PHASES, because that is
exactly what it is. Then he proceeds to do exactly that in the paper.
I provided a link where you can see where he does exactly that, and works
through the math. He teaches electrical engineering.




Abstract:
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.

W. H. Kersting
Milsoft Utility Solutions, USA
W. H. Kersting (SM'64, F'89, Life Fellow 2003) was born in Santa Fe, NM. He received the BSEE degree from New Mexico State University, Las Cruces, and the MSEE degree from Illinois Institute of Technology. He joined the faculty at New Mexico State University in 1962 and served as Professor of Electrical Engineering and Director of
the Electric Utility Management Program until his retirement in 2002. He is currently a consultant for Milsoft Utility Solutions. He is also a partner in WH Power Consultants, Las Cruces, NM.



I also note that I gave everyone here days to just define one phase, two phase,
N phase power. Not one of you "experts" could do it. I did, very simply:


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.

It fits:

one phase
two phase 90 deg
two pahse 179 deg
two phase 180 deg
three phase
five phase
N phase


And I note you can't answer the simple questions a student would ask a
teacher:

The old two phase power was 90 deg over four wires. If it was instead
two phases over 3 wires, a shared neutral, would there still be two phases
present?

If yes, then how about if the phase angle was changed to 179 deg, or
181 deg, would there still be two phases there?

How about 180 deg? Two phases, yes or no?

And if it's suddenly no, then why?

The reason neither of you will address it is because you can't. There
is no rational explanation and it leaves you grasping for straws.

Or how about the other scenarios I gave Fretwell. You have a black box
that generates 5 sine waves coming out of it, one at 120 deg, one at 150,
one at 180, one at 210. Fretwell would have you
believe you need to analyze an entire system to be able to determine
how many phases there are. I say the fact that there are five power
sources coming out, defined by their phase differences is all we need
to know that there are 5 phases there. Where are you on that? Are
there five or not? And if there are 5, why does the one at 180 deg
count there, but not coming into a house?

If there are not two phases, then I should be able to parallel any
two 120V receptacles in the house. Can I do that? No, because some
are 180 deg out of PHASE with the others. Everthing is explained with
basic electricity 101. I have all the questions raised here covered
explained. And it all fits with the IEEE Fellow's paper, 100%.
You two are left grasping at straws with evolving explanations that
make no sense. And once again, neither of you will respond to the
simple questions in the scenarios I put forth. I address all of yours.


All that shows is this guy spends too much time in theory and not
enough time in the real world.
There are plenty of well credentialed people who write gibberish.

It is not 2 phases, it is just one and the reason you can't parallel 2
phases is exactly because it is ONE phase. You are taking the second
half of the sine wave and trying to lay it down over the other side.