Why is residential wiring known as single phase?

[mivey]

Compare Besoeker's current directions to the ones I used, when there is no conductor between the neutral point of the source and the neutral point of the loads, what do you notice?

You notice that you have eliminated two voltage options. You only have one voltage left and it can be assigned a positive direction of either X1->X4 or X4->X1. Before, you had these options for positive voltages:
X1->X4 or X4->X1
X1->X2 or X2->X1
X3->X4 or X4->X3

 

[rattus]

Oh, I'm flexible and adaptive enough to accept anti-phase. Or we can go with bushels per acre if my acceptance is not acceptable.

As anti-phase, this how V_an and V_bn appear when measured on a common time base.

Neither I, nor Jim, nor Rick, nor Rbalex, nor any of several others have disagreed that, to use your words, the two legs appear to be in anti-phase on your scope. Neither do I, and I presume the others as well, disagree that it can be used in that manner for many, many purposes. And as Mivey and I finally came to agreement in a prior thread, unless there is a compelling need to understand otherwise then feel free to call them opposing phases.

The question on this thread was "Why is residential wiring known as single phase?". The question was undoubtedly asked for the same reason you keep defending, and no one is really questioning. When metered or scoped it appears to be two opposing phases. And when used it works like two opposing phases. So why, when it quacks like a duck and looks like a duck is it not called a duck?

To properly answer the question you have to investigate the things that make single-phase different from two opposing phases. There are real differences. But your scope setup will never show them. The test I gave you in the prior post establishes a different time base. It shows a different result. It demonstrates that when you change test conditions then you see different results. But the question isn't "What does residential wiring appear to be?" or "How can residential wiring be used?" rather it asks why it's called what it's called.

You seem to be equating 2 phase angles to 2-phase service. Van and Vbn carry different phase angles. That does not mean we have a 2-phase source. Neither does the 208V @ 90 in a high leg delta mean we have a 4-phase service.
Whatever, it is nonsense to claim Van and Vbn are not antiphase when the scope traces show clearly that they are. It is more nonsense to claim they merely appear to be so.

You are jousting with windmills.

 

[mivey]

What you're displaying is the potential difference between V1 and V2 as the distance between the curves. It's still just a simple voltage divider.

The equivalent in a DC circuit is to connect a load between the two poles of a 24V battery. Then ground the center of the load. Put that on your oscilloscope and the scope will show +12VDC at one end and -12VDC at the other with 0VDC at the ground point. Both the +12V and -12V are very usable voltages. Despite the two measurements, there is still only one source of power moving across those loads.

But in the DC case we have no other phase option so it is not really a good comparison. DC does not change direction like AC.

When one load draws excessively and pulls down power on one source what happens to the other leg?

??? The power gets pulled down on a multi-phase generator when one phase is drug down as well. The whole unit is affected.

Yes, I do. Your voltage measurements may be out of phase, but the windings are not. Or more accurately, "Winding", since it is a single winding with a center tap.

And there is the rub. The forces in the transformer push in the same direction. But they would also do the same thing with sources that are physically displaced by 180?. I have a generator graphic in prior threads showing that exact thing. It is our assignment of one direction to something that can be used in either direction that is the issue. It is the smudging of the terminology used that makes the two topics seem to disagree when they can't physically be in disagreement.

 

[mivey]

Yes, you can get scopes with isolated inputs and I have used them on occasion.
Tend to be a bit pricey and somewhat limited bandwidth.

The differential probes are cheaper. I have a probe that can make this measurment but I don't see the point.

 

[mivey]

Because Bes does not admit the existence of voltages V1n and Vn2 as he does with V1n and V2n!

In what reality? Unless I missed it, he has only said that V1n and Vn2 do not have a common reference point.

So how come Besoeker gets to make up terms like anti-phase and I can't use physics terms like apparent?

Because your membership card has expired. For a nominal fee, I'll get you up to date.

 

[mivey]

The question on this thread was "Why is residential wiring known as single phase?". The question was undoubtedly asked for the same reason you keep defending, and no one is really questioning. When metered or scoped it appears to be two opposing phases. And when used it works like two opposing phases. So why, when it quacks like a duck and looks like a duck is it not called a duck?

That is the same question that keeps coming up. The labels are weak. They are labels, not comprehensive descriptions.

Iwire gave the simple answer long ago.

 

[qcroanoke]

You are jousting with windmills.

I can honestly say I have never (until today) heard or read that expression.
I found this:
Refers to engaging in a futile activity or attacking imaginary enemies. Tilting - as in jousting - at windmills is an expression derived from the novel El ingenioso hidalgo don Quijote de la Mancha by Miguel de Cervantes Saavedra, where the main character of Don Quixote fights windmills that he imagines to be giants.

At least I got something out of this thread..... :0)

 

[mivey]

I can honestly say I have never (until today) heard or read that expression.
I found this:
Refers to engaging in a futile activity or attacking imaginary enemies. Tilting - as in jousting - at windmills is an expression derived from the novel El ingenioso hidalgo don Quijote de la Mancha by Miguel de Cervantes Saavedra, where the main character of Don Quixote fights windmills that he imagines to be giants.

At least I got something out of this thread..... :0)

Good ol' Don Quixote.

Gesundheit!!

 

[CONTROL FREQ]

Good ol' Don Quixote.

Gesundheit!!

Is that anything like throwing a hot dog down a hallway? Cause I did that a few times? NOT GOOD AT ALL, kinda like having your eyeballs assaulted by a walmart woman in a ?baby-tee? HHHHHUUUGH! Windmills however are a fantastic electrical discussion.

 

[CONTROL FREQ]

Because "the powers that be" say it's either 3 phase, or single phase. if you are here in the US, it's 120,208,277,480. Canada may be 500,600, whatever their powers say.... that's the plain truth. sad as it is, 35-70hz is most likely to kill a person, but was chosen by "the powers" (like edison) because of easy math, etc... I honestly believe even he expected us to fix that in time.... we just aren't smart/persistant enough. JMO....

 

[jim dungar]

You notice that you have eliminated two voltage options. You only have one voltage left and it can be assigned a positive direction of either X1->X4 or X4->X1. Before, you had these options for positive voltages:
X1->X4 or X4->X1
X1->X2 or X2->X1
X3->X4 or X4->X3

Those options still exist, in fact you can measure them as source voltages or as voltage drops across the loads. The only thing that changed was a current path, which wouldn't impact the oscilloscope display.

 

[jim dungar]

Originally Posted by jim dungar
How do we show a phase difference in this circuit? I know one method included 'different math techniques' when writing KCL formulas at nodes A, N, and B.
...The "technique" is the direction choice we make and does not change the fact that the voltages produced can be used either way.....

No the technique I was addressing was the use of different KCL formulas 'methods' for two different 2-wire nodes in the same circuit. Effectively these two formulas were 'current entering = current leaving' and 'current entering = current entering'.

 

[jim dungar]

But in the DC case we have no other phase option so it is not really a good comparison. DC does not change direction like AC.

Actually this has absolutely nothing to do with any of the circuit equations and analysis we have been using. When we say 120V AC (RMS inferred), we are effectively creating a single snapshot in time and therefore are analyzing a non-alternating voltage.

The fact that the rectifier circuit works 'over a time period' is due to the diodes. You could create an identical functioning circuit from a POS-0-POS VDC source, (unless you needed the 0V ripple, which I am sure Besoeker doesn't as one reason for his 6-pulse units is to reduce it).

 

[mivey]

Those options still exist, in fact you can measure them as source voltages

They might exist at the source but without the neutral conductor to the load they are not really an option.

...or as voltage drops across the loads.

You will certainly have something at the load, but it won't be X1-X2 or X3-X4 voltages. As you know, this is the floating neutral scenario.

The only thing that changed was a current path.

And that makes all the difference in the world for normal loads. It is also what makes the possibility of more than one circuit current possible. Without the neutral, the current leaving X4 is the same as the current entering X1. With the technically correct definition of phase, you can then only have one phase at any instant in time.

With the neutral the current leaving X4 can be out of phase with the current entering X1. The winding currents can be out of phase as well. With the strict definition of phase, you can have currents out of phase thus you can have two phases present at any instant in time. A separate issue from the single-phase label.

 

[jim dungar]

They might exist at the source but without the neutral conductor to the load they are not really an option.

But Besoeker's oscilloscope would still show two waves.

With the neutral the current leaving X4 can be out of phase with the current entering X1.

Not if you choose the currents directions of 'out of X1 into X2' and 'out of x3 and into x4', which is an absolutely logical method as it mimics the analysis of current flow in 3-phase circuits (which is not part of this discussion).

 

[mivey]

Actually this has absolutely nothing to do with any of the circuit equations and analysis we have been using. When we say 120V AC (RMS inferred), we are effectively creating a single snapshot in time and therefore are analyzing a non-alternating voltage.

I respectfully disagree. The fact that the AC wave alternates is the very reason we can have more than one phase present at any given instant (using the technically-correct definition of phase).

The fact that the rectifier circuit works 'over a time period' is due to the diodes. You could create an identical functioning circuit from a POS-0-POS VDC source, (unless you needed the 0V ripple, which I am sure Besoeker doesn't as one reason for his 6-pulse units is to reduce it).

The diodes are the extreme example of the different phases present. A simpler case is practically any circuit connected to the 3-wire source. At any given time it is almost a certainty that the current leaving X4 will be different from the current entering X1 and will differ in phase. The difference can be small but that makes the difference from saying the two currents are one and the same. With the neutral conductor in use, the currents are not the same but a result of the effect of the neutral conductor forcing the X2/X3 voltage at the intersection of the loads.

 

[mivey]

But Besoeker's oscilloscope would still show two waves.

Connected where?

Not if you choose the currents directions of 'out of X1 into X2' and 'out of x3 and into x4', which is an absolutely logical method as it mimics the analysis of current flow in 3-phase circuits (which is not part of this discussion).

Of course they can be out of phase. Because of the parasitic internal impedance, practically any unbalanced load will do it (to be quite honest, a balanced load would also and becomes noticible at high loading). While these are very small phase differences, it shows the effect of the neutral path. The loads with different impedances just makes it more obvious. The diodes make it extremely obvious.

 

[CONTROL FREQ]

Connected where?

Of course they can be out of phase. Because of the parasitic internal impedance, practically any unbalanced load will do it (to be quite honest, a balanced load would also and becomes noticible at high loading). While these are very small phase differences, it shows the effect of the neutral path. The loads with different impedances just makes it more obvious. The diodes make it extremely obvious.

You sir, are hillarious! And Mivey, I'm sure BESOEKER would show you exactly where to stick them...

--- That's what I saw on the scope! but I got censored.:jawdrop:

 

[jim dungar]

Connected where?

Why, to the source neutral reference that Besoeker and Rattus seem to insist must be used.

What if we had 2-loads but the common conductor was X1?

Of course they can be out of phase.

Are you saying they cannot be in-phase?

 

[Besoeker]

Why, to the source neutral reference that Besoeker and Rattus seem to insist must be used.

What if we had 2-loads but the common conductor was X1?
View attachment 6422

N would still be common to node A and node B