240v debate....

[Besoeker]

Mivey made the following comment yesterday and I started to write a follow-up to it several times but decided not to because it was relating something he was saying to something you were saying. With your new posting, his words are again re-applicable.
I don't want to put words in your mouth (Besoeker), but for quite some time during this discussion, you have made statements and assertions that seem to imply that you believe there is one way and only one way to view a system. Your adamancy on this viewpoint is the reason why I began to wonder whether you had obtained the original viewpoint education that I know is present in engineering coursework. (No insult intended. I am just explaining why I had previously questioned it.)

I had asked you several days ago whether you asserted that the 180 degree phase shift was absolute and independent of viewpoint, and you asserted that it was, but never responded to the discussion after that point. So I will ask again. Are you under the belief that the 180 degree phase shift is present irrespective of whether the neutral is chosen as a common reference point?

Why don't you just answer the question I asked?

 

[Besoeker]

ITHAT is what Mac contributes to immeasurably AND patiently.

If I'm the Mac you refer to, then I am humbled by that.
If I'm the wrong Mac, I wish the other the patience of Job and the wisdom of Solomon.

 

[jim dungar]

Also agreed and I have not disputed either of those points.

Then the flux in the single core, must produce similiar results in both top and bottom halves of a single winding, even if the winding has three terminals on it.

Physics gives us the starting points, how we 'view' them is what is arbitrary.

Eventually we will get end up discussing vectors/phasors and the math when they are connected head to tail, versus tail to tail.

 

[mivey]

Then the flux in the single core, must produce similiar results in both top and bottom halves of a single winding, even if the winding has three terminals on it.

It is no different than the results you would get from the top and bottom "halves" made from the flux in separate cores, or even the joining of the separate cores. The relationship at any instant in time is not an indicator that one direction across both windings is positive and the other direction is negative.

The single flux does not tell us that the direction we take the voltage for both halves must be the same. What about the "laws" tells you that one direction is "true" and the other direction is a math trick? The truth is, there is no law telling you that they must be taken the same, and if you think so I say post it and prove it.

With separate cores, we can prove that the positive wave of the "up" half is in phase with the negative wave of the "down" half. We can also use the positive forces from either end of the winding and show that these two positive forces have a 180? displacement. Polarity is a relative relationship and there is no universally "correct" direction.

The simple fact is that there is a positive pressure in both directions because the polarity is changing every 1/2 cycle. That is not the same as the battery case that keeps getting cited because the polarity never changes for the batteries.

 

[mivey]

So if a tree falls in the forest it gets a shock?

I guess that depends on if it contacted a real voltage or a voltage made up of a bunch of math tricks.

 

[Rick Christopherson]

Isn't connecting something in phase order ABC and BAC is simply CHANGING one's chosen 'reference' point? Will it produce different results in a 3 phase motor rotation?

That's not a change in reference. That's a change in the physical circuit.

Does a connected motor change its direction of rotation when you put your voltmeter probes on the terminals? No. In order to get reversal, you need to unbolt two physical wires and reverse them.

 

[jwelectric]

I would disagree. They can serve two entirely separate circuits and have completely different currents. They are serving as two single-phase sources when taken separately, or as one combined double-voltage, single-phase source when the neutral is not used.

Would not the total current on the center tap be the difference between the two halves and the remainder of the current be flowing through both halves? Then how can they be out of phase by even one degree?

 

[Rick Christopherson]

The single flux does not tell us that the direction we take the voltage for both halves must be the same. What about the "laws" tells you that one direction is "true" and the other direction is a math trick? The truth is, there is no law telling you that they must be taken the same, and if you think so I say post it and prove it.

Yes it does and I did post those laws. You dismissed them offhandedly. You're accustomed to dealing with transformer equations on the macroscopic level, but seem to forget that they have their origination at the atomic level, with forces acting on the physical electrons.

 

[mivey]

How can one's chosen reference point impact how a circuit functions?

That's not a change in reference.

Then take a motor that is wye connected with a common neutral reference point and move the common point to one of the phase conductors.

 

[mivey]

Would not the total current on the center tap be the difference between the two halves and the remainder of the current be flowing through both halves? Then how can they be out of phase by even one degree?

You said they were not two sources. A single voltage source has two terminals. By definition, a voltage is taken between two points.

 

[Rick Christopherson]

Then take a motor that is wye connected with a common neutral reference point and move the common point to one of the phase conductors.

That is a physical change in the circuit too. Can you make this change without a screwdriver or wrench?

 

[mivey]

Yes it does and I did post those laws. You dismissed them offhandedly. You're accustomed to dealing with transformer equations on the macroscopic level, but seem to forget that they have their origination at the atomic level, with forces acting on the physical electrons.

I am accustomed to dealing with transformers equations at any level you would like to discuss. Deal with them at any level you want.

You will find that none of the equations you want to bring up will tell you that Van and Vbn are not displaced by 180?. Neither will any of them tell you that Vnb is a real voltage and Vbn is just a math trick.

None. Nada. Never gonna happen.

 

[mivey]

That is a physical change in the circuit too. Can you make this change without a screwdriver or wrench?

Can you take your two-wire meter and measure Van and then measure Vnb with out making a physical change? Please go try that and come back here and report your findings. Remember that the meter is just a load.

 

[weressl]

That's not a change in reference. That's a change in the physical circuit.

Does a connected motor change its direction of rotation when you put your voltmeter probes on the terminals? No. In order to get reversal, you need to unbolt two physical wires and reverse them.

Nope, IF the generating source can be reversed WITHOUT any physical change.

 

[weressl]

Yes it does and I did post those laws. You dismissed them offhandedly. You're accustomed to dealing with transformer equations on the macroscopic level, but seem to forget that they have their origination at the atomic level, with forces acting on the physical electrons.

THAT theory about electricity is somewhat outdated.

 

[weressl]

Then the flux in the single core, must produce similiar results in both top and bottom halves of a single winding, even if the winding has three terminals on it.

Physics gives us the starting points, how we 'view' them is what is arbitrary.

Eventually we will get end up discussing vectors/phasors and the math when they are connected head to tail, versus tail to tail.

We already been through this, right?

 

[hurk27]

The single flux does not tell us that the direction we take the voltage for both halves must be the same. What about the "laws" tells you that one direction is "true" and the other direction is a math trick? The truth is, there is no law telling you that they must be taken the same, and if you think so I say post it and prove it.

With separate cores, we can prove that the positive wave of the "up" half is in phase with the negative wave of the "down" half. We can also use the positive forces from either end of the winding and show that these two positive forces have a 180? displacement. Polarity is a relative relationship and there is no universally "correct" direction.

Not sure what you mean by relative, but I wouldn't use that when paralleling the two windings of the secondary of a transformer, putting X1 with X4 and X2 with X3 might get some unwanted results.:blink:

 

[Rick Christopherson]

Not sure what you mean by relative, but I wouldn't use that when paralleling the two windings of the secondary of a transformer, putting X1 with X4 and X2 with X3 might get some unwanted results.:blink:

Why not? It's not like it would violate any of these flexible laws of physics.

 

[hurk27]

Originally Posted by hurk27
This site here explains it fairly well:

http://www.allaboutcircuits.com/vol_2/chpt_10/1.html

About half way to the bottom.

And if you can see that, I'll say you & I are in agreement up to this point like I think Rick & I are in agreement up to this point. Jim should be, but I really do not know if he can agree that you can have two 180? displaced sources without playing math games with the terminals.

If you agree with what this site had to say then you would also agree with this point they made almost at the bottom of that page I posted:

Power systems in American households and light industry are most often of the split-phase variety, providing so-called 120/240 VAC power. The term ?split-phase? merely refers to the split-voltage supply in such a system. In a more general sense, this kind of AC power supply is called single phase because both voltage waveforms are in phase, or in step, with each other.

 

[Besoeker]

Eventually we will get end up discussing vectors/phasors and the math when they are connected head to tail, versus tail to tail.

I thought I had been clear and consistent about this.
V1-N and V2-N are mutually displaced by 180deg. See post #22.
OK, to line up with other definitions I have later referred to them as Van and Vbn. They are also mutually displaced by 180deg.
One simple fact.
That's all.
What's to discuss further?