May I ask a question about the single vs two phase stuff

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Ingenieur

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jaggedben said:
What's the difference? Also, we are using mathematical expressions to approximate what we see in the world. The voltages are not a 'consequence' of the math at this level of physics. It's the other way around.

I still don't think I received adequate responses to my post 241.
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not sure you will ever be satisfied after 40 pages, so why try?
 
jumper

jumper

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jaggedben said:
We're not relying on the battery analogy when stating that if voltage L1-N can be derived from sin(x) then voltage L2-N can be derived from -sin(x).
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I understand that. Wayne discussed his reasoning. Not a problem. Took me a sec to go back and see the math and how it was derived. But okay, just not for me in this application.

My problem is that it is not standard methodology at an applied electrical level.

No need to complicate an already confused situation IMO.
 
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jaggedben

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Solar and Energy Storage Installer
jumper said:
...

My problem is that it is not standard methodology at an applied electrical level.
...
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And I'm not going to debate what is 'standard methodology' in the engineering field. My point is that for many day-to-day applications in electrical installation, polarity works just fine on these services when using phasor math would add time and money to a project. In fact, for resistive loads it produces the same mathematical resuslts. For waveforms where distortion matters I'm unconvinced it doesn't work better. Why is this so hard for some here to accept? I think you get it, just not sure about all others.
 
jumper

jumper

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jaggedben said:
And I'm not going to debate what is 'standard methodology' in the engineering field. My point is that for many day-to-day applications in electrical installation, polarity works just fine on these services when using phasor math would add time and money to a project. In fact, for resistive loads it produces the same mathematical resuslts. For waveforms where distortion matters I'm unconvinced it doesn't work better. Why is this so hard for some here to accept? I think you get it, just not sure about all others.
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Totally accept all. I got no problem with alternative methods where parameters change.
 
Besoeker

Besoeker

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LarryFine said:
To me, if it was two phases, it would be two regardless of the reference point.
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But different amplitudes. The 120-0-120 are in anti-phase, not the same phase. That's why the neutral current cancels, and that's the raison d'etre for this configuration.
 
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buffalonymann

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winnie said:
It doesn't matter if it is one coil with a center tap or two coils with a jumper. The coils consist of individual turns and the individual turns are electrically in series, and the center tap is simply connected to one of the turns (either directly or via the x2 x3 leads). They are equivalent.

It is a single phase transformer. Everyone here agrees that it is a single phase transformer. There is approximately a single flux coupling all of the turns of the coil (only approximately; remember leakage inductance). All of the turns of the coil develop approximately the same voltage.

That does not change the fact that there are _two_ apparent phase angles, that you can use these _two_ phase angles to do correct math describing the operation of the transformer and the neutral.

The _fact_ that you can do correct math to give correct predictions using phase angles of 0 and 180 is sufficient to make clear that the two phase angles are present. They are related by inversion, they are in some senses the same (zero cross at the same time), and by alternate selection of reference you can change the system to have only a phase angle of 0. But you can still do correct math with _two_ phase angles. We agree not to call the system a 'two phase' system, but clearly there are two phase angles available.

-Jon
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Electrical theory governs. The sine wave L1-N and N-L2 are in phase, and if the correct math was applied, the same result would be achieved.
 
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Ingenieur

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buffalonymann said:
Electrical theory governs. The sine wave L1-N and N-L2 are in phase, and if the correct math was applied, the same result would be achieved.
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:happyno:

electrical 'theory' (or 'physics') and math confirm each other

1/0
1/180

1/0 = 1 + 0j
1/180 = -1 + 0j

Vll = 1 + 0j + (-) (-1 + 0j) = 2 / (arctan 0) = 2/0

where is the math 'incorrect'?
 
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W

winnie

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Springfield, MA, USA
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Electric motor research
buffalonymann said:
Electrical theory governs. The sine wave L1-N and N-L2 are in phase, and if the correct math was applied, the same result would be achieved.
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If the math works to correctly predict the physical world, then the math is correct.

The math matches the electrical theory.

The fact is that you can do the math multiple different ways and get the same result.

All of these approaches are correct.

L1-N and L2-N are part of the same single phase system. They can quite reasonably and correctly be represented by two vectors, one 120V at 0 degrees and 120V at 180 degrees. That you _choose_ to use a different representation does not make this incorrect.

-Jon
 
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