On Wed, 11 Sep 2019 17:32:47 -0700 (PDT), trader_4
wrote:

On Wednesday, September 11, 2019 at 4:37:34 PM UTC-4, wrote:
On Tue, 10 Sep 2019 17:43:33 -0700 (PDT), trader_4
wrote:

On Tuesday, September 10, 2019 at 8:22:06 PM UTC-4, wrote:
On Tue, 10 Sep 2019 14:01:50 -0400, devnull wrote:

On 9/10/19 1:05 PM, trader_4 wrote:
You might want to improve your reading comprehension skills. Neither I
nor the professor said that we would call it two phase. Only that what
is actual there are two voltage sources, two phases that are 180 deg out
of phase with each other.

You only *appear* to have two phases when you hook one pair of your oscilloscope leads up backwards.

Actually you mean when you hook your scope up in the center of the
single phase winding. I can do the same thing with 2 AA cells and make
it look like the plus end of one battery is actually minus.

Yes, how very unreasonable to hook up a scope using the system neutral,
the system reference point. Is that like an unfair magic trick?
And no, it's not hooking up the scope
backwards. Connect the ground clip to the SYSTEM NEUTRAL. Connect
one probe to L1 you get one sine wave. Connect the other probe to
L2, you get the inverse, 180 phase difference sine wave. Which of
course is exactly what the power source is, two sine wave sources
that are 180 out of phase with each other.

OK so you admit what you see is just an artifact of where you hook up
your scope.

No, it's not an artifact, you're seeing exactly what is there.
You act like I want to hook the scope ground to some bizarre point,
like out in space or tied to a water bucket. In fact, it's being
hooked to the neutral, which is the common system reference point.
Do you deny that 240/120 looks like and behaves exactly like two
120V voltage sources that are 180 deg out of phase with each other?

And again, if you would follow the very simple example I gave using
Ralph's 90 deg two phase, you'd see how electrically it is the same
as 240/120 with the exception that the phase angle is 180, instead of
90. Again:

Ralph's two phase is two phase, yes? It was three wires, 0 deg
phase hot, 90 deg phase hot, common neutral return, yes? OK,
make it 100 deg phase difference, which of course we could easily
do. Would there still be two phases
there? Make it 179, still two phases? Make it 180, what do you have
now? Still two phases or did something mysterious just happen?
And don't say those phases are "weird", it's irrelevant. We can
write the equations, solve them, for any phase angles we want.
Of course the answer is that there are still two phases there.
And then what you have is electrically the same as the 240/120 service.
They are indistinguishable. That's the beauty when you approach
things like an engineer, logically. If you don't treat it that way,
then you have holes where what should be elegant, logical and
continuous, falls apart.

There is nothing bizarre with corner grounded delta and any single
transformer is exactly like the one in front of your house.