Center-tap Transformer Voltages

[mivey]

Because the neutral at your house is exactly 0 volts. Just like the voltage at my house is 0 volts. And if we measure between them we would get 0 volts?

Nope. But the voltage you measure between them is the voltage between them, not just an appearance of voltage.

It's why we use a building grid. If we drove separate rods for each machine we'd shock everyone with the potential difference between different machines. 0 volts is a fiction except in relative measurements.

That's right: zero is what we want it to be. That's why the voltage measured between two points, with a conservative field, is about as close to absolute as you are going to get.

Measuring between two points is called relative not absolute.

A point does not have a voltage so that is as close to absolute as you will get for a voltage.

Yea! I got a smiley!

Here, have another . And one for the road .

The question would be whether you've ever used the word "apparent" in its scientific application.

Of course. I just prefer to use it where applicable.

Unless you're proposing that we can't borrow words from other disciplines. In which case I'll have to concede that George is right.

We can bunch together any number of words we want. Whether or not that grouping will makes sense is a different matter.

 

[Rick Christopherson]

A point does not have a voltage so that is as close to absolute as you will get for a voltage.

Actually a single point can have a voltage. It is an energy state. Even though we have a hard time defining it from absolute does not mean it doesn't exist. It is no different from other energy states such as temperature or gravity. And like temperature or gravity, there is no such thing as a negative voltage on the absolute scale. Negative comes in only when dealing with relative differences and charge polarities.

 

[pfalcon]

Seems there is no reference forthcoming, so we must assume that you just made up this term and are trying to justify your usage of the term by your endless arguments.

You got three for the usage of the adjective "Apparent" so you've got your quota for 1984.

Nope. But the voltage you measure between them is the voltage between them, not just an appearance of voltage.
That's right: zero is what we want it to be. That's why the voltage measured between two points, with a conservative field, is about as close to absolute as you are going to get.
A point does not have a voltage so that is as close to absolute as you will get for a voltage.
Here, have another . And one for the road .
Of course. I just prefer to use it where applicable.
We can bunch together any number of words we want. Whether or not that grouping will makes sense is a different matter.

But you gave my smiley away to jaggedben :?

I had a whole bunch of stuff typed in to what you replied; but answering just widens the discussion again so I'm gonna try once again to narrow it.

1) If we are limiting this discussion purely to the specific reference frame where we ignore the primary-secondary transformer linkage and attach our reference probe to the neutral then the words "apparent" and "relative" don't add anything to the discussion. And we ought to have been done with this discussion long ago.

2) But if you want to know why Rick Christopherson and I originally said both coils on the secondary were in-phase and in-polarity then you have to accept using the underlying science. There the words "apparent" and "relative" have meaning. I think that Rick has almost given up that anyone could possibly care.

mivey, please let me know whether you are happy with being 100% absolutely, positively correct under #1; or whether you wanted to explore #2. Because all my aborted replies to your prior post are only relevant under #2.

 

[rattus]

You got three for the usage of the adjective "Apparent" so you've got your quota for 1984.

Back on that tack are we? Where is the reference for "apparent voltage"?
I strongly suspect there is none. I can't find one either.

 

[pfalcon]

Back on that tack are we? Where is the reference for "apparent voltage"?
I strongly suspect there is none. I can't find one either.

Never left it. See post #163. Since you're only interested in the conditions of item #1, any further discussion of terminology is pointless.

 

[rattus]

Never left it. See post #163. Since you're only interested in the conditions of item #1, any further discussion of terminology is pointless.

Pointless, because you can't produce a reference that doesn't exist!

 

[jim dungar]

Where is the reference for "apparent voltage"?

You need to stop quoting words out of context.

Please go back to post #100 where you talk about 'apparent scope traces'.
It is apparent the discussion is about voltages resulting from different measurement techniques and not about real vs unreal.

 

[rattus]

For what it's worth:

For what it's worth:

BTW, we can tie X2 and X3 to separate references (not recommended) and the waveforms seen at X1 and X4 are still 180 out of phase.

 

[pfalcon]

BTW, we can tie X2 and X3 to separate references (not recommended) and the waveforms seen at X1 and X4 are still 180 out of phase.

An amazing observation!
BTW, we can tie X2 and X3 to separate references (not recommended) and the waveforms seen at X1 and X3 are still 0 out of phase.
BTW, we can tie X2 and X3 to separate references (not recommended) and the waveforms seen at X2 and X4 are still 0 out of phase.

And exactly when did you last see a 240/120 transformer that split the secondary coil into two pieces? Just curious.

 

[mivey]

Actually a single point can have a voltage. It is an energy state. Even though we have a hard time defining it from absolute does not mean it doesn't exist.

For clarity: you are not talking about electron-volts are you? Your reference to energy makes me thing you might be, but I don't want to assume.

 

[mivey]

But you gave my smiley away to jaggedben :?

Not sure what happened other than I was half asleep.

1) If we are limiting this discussion purely to the specific reference frame where we ignore the primary-secondary transformer linkage and attach our reference probe to the neutral then the words "apparent" and "relative" don't add anything to the discussion. And we ought to have been done with this discussion long ago.

I'll just guess that we might be on the same page but are just separated by some terminology. Not really an issue I suppose.

But if you want to know why Rick Christopherson and I originally said both coils on the secondary were in-phase and in-polarity then you have to accept using the underlying science.

There is also underlying science for the other option as well. I think the problem is that some are trying to make the underlying science say something that it is not saying.

There the words "apparent" and "relative" have meaning. I think that Rick has almost given up that anyone could possibly care.

I'm about played out on the whole "apparent" thing myself.

please let me know whether you are happy with being 100% absolutely, positively correct under #1; or whether you wanted to explore #2. Because all my aborted replies to your prior post are only relevant under #2.

I am happy with ignoring the primary to secondary linkage but I do not have a problem using it either. Either method is fine.

There is no conflict with #2 either. I am in agreement with the polarity rules as well. I just do not agree that these instantaneous current relationship between the primary and secondary have to be used to define one "correct" direction for both secondary voltages. The secondary winding halves have forces that can be used either way and using them either way is not in conflict with the underlying science.

There is a difference between polarity and direction. This can be shown by being able to align the instantaneous forces of both in-phase and phase-opposed voltages. The instantaneous data (the polarity) is simply not the same thing as the direction we take for positive or negative. That is the tie that is not there and the science will not say is there because it simply ain't. The science addresses two different things. Even if those two different things are related somewhat, they are not the same thing and you can't make one define the other.

 

[pfalcon]

re: 163 #2

re: 163 #2

... A point does not have a voltage so that is as close to absolute as you will get for a voltage. ...

Actually a single point can have a voltage. It is an energy state. Even though we have a hard time defining it from absolute does not mean it doesn't exist. It is no different from other energy states such as temperature or gravity. And like temperature or gravity, there is no such thing as a negative voltage on the absolute scale. Negative comes in only when dealing with relative differences and charge polarities.

For clarity: you are not talking about electron-volts are you? Your reference to energy makes me thing you might be, but I don't want to assume.

Is this an election to delve into the more esoteric science behind electricity? (163 #2)

Sorry Rick, I gotta go with Mivey on this one only in the strictest sense. Yes, every point has a potential energy associated with it which is typically unknowable against an absolute. But as voltage is defined as the "difference" in potential (electrical energy) between two points you must define a second point before calling it a voltage. Properly visualized if you place both probes on the same point then there is "no voltage" and placed on two equi-potential points there are "zero volts" in magnitude.

Of course, along with that esoteric nonsense is that we call things like neutrals and grounds "0 volts". Since there is no absolute reference there is no value that can be placed upon it without a second point being defined. And then the voltage is best expressed as a magnitude and direction, not plus not minus and certainly not one of them being zero.

Unless of course we all want to go back to 163 #1; in which case all of this is just esoteric nonsense.

 

[rattus]

Doesn't Matter:

Doesn't Matter:

An amazing observation!

And exactly when did you last see a 240/120 transformer that split the secondary coil into two pieces? Just curious.

Doesn't matter, no one is going to do it anyway.

 

[pfalcon]

Not sure what happened other than I was half asleep.
I'll just guess that we might be on the same page but are just separated by some terminology. Not really an issue I suppose.
There is also underlying science for the other option as well. I think the problem is that some are trying to make the underlying science say something that it is not saying.
I'm about played out on the whole "apparent" thing myself.
I am happy with ignoring the primary to secondary linkage but I do not have a problem using it either. Either method is fine.
There is no conflict with #2 either. I am in agreement with the polarity rules as well. I just do not agree that these instantaneous current relationship between the primary and secondary have to be used to define one "correct" direction for both secondary voltages. The secondary winding halves have forces that can be used either way and using them either way is not in conflict with the underlying science.

There is a difference between polarity and direction. This can be shown by being able to align the instantaneous forces of both in-phase and phase-opposed voltages. The instantaneous data (the polarity) is simply not the same thing as the direction we take for positive or negative. That is the tie that is not there and the science will not say is there because it simply ain't. The science addresses two different things. Even if those two different things are related somewhat, they are not the same thing and you can't make one define the other.

Crossing posts

I'll forgive you for giving my smiley away :angel:

re: 163 #2
In a typical transformer the secondary coil is one continual coil with a center-tap. By definition it must be in-phase and in-polarity for the entire length of that coil. Hence X1-X2, X3-X4, X1-X4 must all be in one direction. AFTER you reduce this to an equivalent circuit then it only matters to a purist. Because as you state, the forces can be used either way. This isn't a conflict, just a typical case of pragmatism vs technicality.

Agreed. There is a big difference between polarity and direction. Truthfully by the underlying science polarity requires a reference just as voltage does. A transformer only defines both secondary halves being in-polarity as a reference to its own coil. Which is why when the neutral is given as the reference the whole relationship changes. Using the neutral as a reference then the halves are opposing polarities.

Direction on the other hand is a completely obfuscated (like that word?) concept. The only correct "direction" present is that power is flowing from the hot side half the time and from the neutral side the other half cycle; both flowing toward the load. The concept of direction used in circuit diagrams though is a false concept of current from "hot to neutral". The first thing is that we call DC positive when it opposes the movement of the little electron buggers. Then for AC we gracelessly ignore it when they turn around and head the other way. Apparently electrons must be evil because we have a negative impression of them. The choice of direction is therefore fairly arbitrary regardless of reference. You just have to be consistent.

So polarity requires a reference and direction requires consistent use. Which makes them pretty much different things.

And though we arrived at that through different thought paths, we are in total agreement: Polarity and direction are not the same.

 

[pfalcon]

Doesn't matter, no one is going to do it anyway.

Yea! I'll even give you a second smiley

And as you're only interested in 163 #1 I'll make this statement in reference to it:

You are and have always been correct about the measurements, equations, and concepts you've been promoting.

Just don't look at 172 or 174 as they only pertain to 163 #2

 

[mivey]

The only correct "direction" present is that power is flowing from the hot side half the time and from the neutral side the other half cycle

Oh no. Don't think like that at all. Charge carriers don't "deliver" energy like a bunch of coal cars, even though that analogy is sadly used in many school texts. The energy flows towards the load down both wires on both halves of the cycle. Think of the wire pair more like a waveguide.

Then for AC we gracelessly ignore it when they turn around and head the other way.

We also ignore the transient state of current flow. The charges do not smoothly make a turn but the whole process is more of a sloshing back and forth until we reach reach the charge flow that we are accustomed to seeing at a higher level. Even the motion in one direction with DC is not smooth but takes time to settle down to more of a "steady-state" condition with lots of "sloshing" happening first.

And though we arrived at that through different thought paths, we are in total agreement: Polarity and direction are not the same.

 

[pfalcon]

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