Why is residential wiring known as single phase?

[Besoeker]

If you happened to have read Post 132, you would note I said, 'The real question is not why residential voltages are called “single phase” but why Y-connected secondaries of three winding transformers aren’t described as “six-phase”.' It is actually "three-phase wye" and your "hexaphase" that are the "conventional" descriptions if the line-to-line voltages aren't considered.

At the risk of repeating this ad nauseam, the hexaphase arrangement is just line to neutral voltages.There are no line to line voltages involved.

Here's the three phase WYE arrangement:

And here are the voltages WRT neutral:

And here's the hexaphase arrangement:

And, again, the voltages WRT:

Don't you see the difference?

 

[rbalex]

At the risk of repeating this ad nauseam, the hexaphase arrangement is just line to neutral voltages.There are no line to line voltages involved.

Here's the three phase WYE arrangement:

And here are the voltages WRT neutral:

And here's the hexaphase arrangement:

And, again, the voltages WRT:

Don't you see the difference?

Bes, I see three sets of sine waves, all with periods of 2π, all beginning at t₀=0 with three different φ₀: ωt+0, ωt+π/3 and ωt+2π/3. Can?t you see that?

 

[rbalex]

Bes, I see three sets of sine waves, all with periods of 2π, all beginning at t₀=0 with three different φ₀: ωt+0, ωt+π/3 and ωt+2π/3. Can?t you see that?

Rather than editing after the fact: φ₀: 0, π/3, 2π/3.

 

[david luchini]

Do you see my arguement that usually the notation systems are chosen to convey insight, understanding, and describe an underlying physical reality.

No I do not. As pointed out, the notations can be anything you want them to be. There's nothing wrong with using Van and Vnb, just as there is nothing wrong with using Van and Vbn. If I gave you Vbn=120<0 and Vna=120<0, would you be able to tell me what Vab is? Or would it cause problems because the "dots" say the transformer is connected Van and Vnb, not Vbn and Vna?

Do you see my arguement that pounding the table on the phase shift obscures the actual physical reality...The phasor measuring convention does not convey this essential information and the phase shift crowd relies on omitting this essential informaton.

Again, no I do not. It does not matter which convention you use to list your phasors, all the information you need is still contained therein. In a three phase system, with voltage vectors of Van=120<30, Vnc=120<-30 and Vbn=120<-90, can you not still glean all of the information you need for the system, even though the phasors are only 60 degrees apart?

The phasor convention makes the single phase case appear to be similar in character to the three phase case, when it is not.

I don't see that the phasor convention makes the single phase case "appear to be similar" in character to the three phase case. Not any more than the phasor convention would make a two phase case appear similar to the three phase case, or the three phase case appear similar to the nine-phase case, etc. I think you are projecting these "similarities" onto the phasors for the sake of argument.

As long as you properly apply the phasor combining conventions, it does not matter how many phases are in the system, or how the phasors are represented. I would be able to correctly find Vab, Vbc and Vca in a three phase system if my voltage phasors are Van=120<0, Vbn=120<-120, and Vcn=120<120, and I would be able to find Vab, Vbc and Vca in a three phase system if my voltage phasors are Van=120<30, Vnc=120<-30 and Vbn=120<-90.

 

[Besoeker]

Bes, I see three sets of sine waves, all with periods of 2π, all beginning at t₀=0 with three different φ₀: ωt+0, ωt+π/3 and ωt+2π/3. Can?t you see that?

Three sine waves:

Six sine waves:

 

[mivey]

I will try to be more careful in the future. I believe the stamp is automatic. Usually the edits without comment were just to correct spelling or grammar. When there was a substantive change I usually add an "edit add" statement or acknowledge it in an immediate response as I did with you.

I'll trust you have been careful and I have no reason to believe you would act otherwise. But that is not the only issue. Readers may browse a thread and take note of what was said. Making changes much later is simply not fair to the reader who thinks he has kept up with what was said.

I rarely keep backing up in a thread to see if anyone made changes. I used to have to do that and it was tiresome sometimes. I really like the new time limit, except when I find I posted a blunder and have to make another post to correct it. But that is fairer to those trying to follow along.

If I recall correctly, the time limit was shortened after we had a crazy member re-edit what he said almost as fast as we could reply. We started re-quoting what he posted to keep it straight. It really was an amusing exercise but would not be fun all the time. Of course, you have done nothing like that and I do not think you would.

This is why I attempt to inquire (Are you saying...?) rather than declarative (You are saying...) It permits the other person to correct misimpressions, if necessary. As I said I'll try to be more careful in the future; but I don't believe I've ever intentionally misunderstood anything - nor tried to misdirect the discussion.

But you have posted insults and made ridiculous statements about member's abilities and qualifications and that does get the thread off topic. It also hinders a good debate. I have been guilty of doing the same but I have tried to stop as it is distasteful and petty. It is better to debate what was said without including negative commentary about the person saying it.

 

[rbalex]

Three sine waves:

Six sine waves:

Yes, the three sine wave have the same phases as your hexaphase system - thats why it's a glorified three-phase system. Don't all the hexaphase sine waves, have periods of 2π, begin at t₀=0 each with an effective φ₀ taken from the set[0, π/3 and 2π/3]?

 

[mivey]

Do you see my arguement that usually the notation systems are chosen to convey insight, understanding, and describe an underlying physical reality. In the windings themselves, there are a lot of weird and magical things that could be going on. It would be easy to claim, by magic. That's how I see the question. What is really giong on physically. Is there a phase shift.

We do not shift Van to get Vbn. They are both already there. By phase shift we are recognizing that these are physically different. We do not physically have to add Van to Vnb to get Vab. All three voltages are already there. We do not physically have to subtract Vbn from Van to get Vab. These voltages co-exist. The fact that we have Vab does not mean there is no Vbn.

The 180? phase shift is recognizing the physical difference in the voltages Van and Vbn, not that we had to physically shift Van by 180? to get Vbn. These phase displacements are there because these voltages are physically there at the transformer. We can take the ones we want.

In a 2-phase to 3-phase bank, the output voltages are shifted relative to the input voltages. That is not because we time-shifted the voltages, but because we made use of physical voltages that exist in the transformer to create different physical voltages.

In my open-wye example, I used winding voltages in two different directions to create a new voltages that was shifted 120? relative to the other voltages. These are shifts due to physical changes we make, not time shifts. Voltages are dependent on relative relationships and there is no one set correct and universal reference.

In the three phase case yes there is a phase shift internally in the transformer.

Tell me how. When you can understand that, you will understand the phase shift in the single-phase transformer.

In the single phase case, no, there is not a phase shift internally in the transformer. There are two windings that are the same and matched in every actual physical characteristic.

No they are not. For starters, one has the common point at the polarity mark and one has the common point at the non-polarity mark. The fluxes will not always be the same for each half either.

240 is created from 120 by connecting two of these in series, adding a second winding to the circuit.

But we do not get Vab by summing Van and Vnb. Vab co-exists with Van and Vnb (as well as with the other voltages).

Do you see my arguement that pounding the table on the phase shift obscures the actual physical reality.

Not if one understands the physical reality.

The phasor convention makes the single phase case appear to be similar in character to the three phase case, when it is not. For three phase there is a phase shift and this is shown by the measurments. For single phase there is no phase shift, however a phase shift, the special case of reversing the leads = 180 deg, can create a 180 deg phase shift. The crowd claims there is a phase shift (implying it is internal to, or caused by, the transformer) and not that they created the phase shift external to the transformer by how the leads are attached.

My open wye example creates a third phase by reversing the voltages relative to the other phases. It is a simple thing and should not be over-looked.

It is obfuscation.

No. It is an attempt to clarify for those who can look beyond what they have mistakenly accepted as a complete picture.

 

[rattus]

In the three phase case yes there is a phase shift internally in the transformer.

.

Care to restate that?
There are three single phase transformers in a 3-phase bank.

 

[mivey]

.

Care to restate that?
There are three single phase transformers in a 3-phase bank.

I figured he meant the 30? or 210? phase shift from primary to secondary in a delta-wye connection.

 

[rbalex]

...
But you have posted insults and made ridiculous statements about member's abilities and qualifications and that does get the thread off topic. It also hinders a good debate. I have been guilty of doing the same but I have tried to stop as it is distasteful and petty. It is better to debate what was said without including negative commentary about the person saying it.

Sorry I missed this I saw Bes' post and just skipped it.

I'm happy to keep this civil. The insults, I'm mostly ashamed of and have apologized for most of them, although I've never received one. As for "ridiculous statements about member's abilities and qualifications" is seems that the opposition can dish it out but not take it.

You may not agree with my position and aren't obligated to. But it is clearly substantiated by the definitions I have used as I have used them. Since you haven't accepted or submitted any, you aren't actually in the position to debate anyway.

 

[rattus]

Hexaphase:

Hexaphase:

rbalex:

I see six different phase angles in the hexaphase rectifier. Six phase angles, six phase constants, six phases.

To be of the same phase, the waves must carry the same phase angles. No two of them do. Therefore, none of them are in phase, and none of them are of the same phase, so why keep beating on this dead horse?

 

[__dan]

We do not shift Van to get Vbn. They are both already there. By phase shift we are recognizing that these are physically different. We do not physically have to add Van to Vnb to get Vab. All three voltages are already there. We do not physically have to subtract Vbn from Van to get Vab. These voltages co-exist. The fact that we have Vab does not mean there is no Vbn..

I have never considered that the opposite voltage is not there, just that in this case it is created by swapping the connection leads.

The 180? phase shift is recognizing the physical difference in the voltages Van and Vbn, not that we had to physically shift Van by 180? to get Vbn. These phase displacements are there because these voltages are physically there at the transformer. We can take the ones we want.

Yes, but the disagreement is over the description of what causes this phase shift. It is equal or equivalent to a 180 deg phase shift. But it is not caused by a phase shift. It is caused by reversing the leads relative to the winding turn direction. The transformer itself is homogeneous, the connection causes the difference.

In a 2-phase to 3-phase bank, the output voltages are shifted relative to the input voltages. That is not because we time-shifted the voltages, but because we made use of physical voltages that exist in the transformer to create different physical voltages.

In this case you combine sources that do have a time shifted phase difference, caused by their origin at the generator and carried through the system.

In my open-wye example, I used winding voltages in two different directions to create a new voltages that was shifted 120? relative to the other voltages. These are shifts due to physical changes we make, not time shifts. Voltages are dependent on relative relationships and there is no one set correct and universal reference.

Again the sources available for combination do have a phase shift that is carried through the system, two cores with two phase displaced fluxes.

Tell me how. When you can understand that, you will understand the phase shift in the single-phase transformer.

No they are not. For starters, one has the common point at the polarity mark and one has the common point at the non-polarity mark. The fluxes will not always be the same for each half either.

Most likely the transformer has overlapping windings sharing a uniform single flux. I believe you are referring to possible differences in current flow in the secondary windings which would have a flux difference equivalence. The difference would be caused by the difference in the current flow between the windings and not by differences in the shared flux. The windings share the same flux but can have different loads and different current flows.

But we do not get Vab by summing Van and Vnb. Vab co-exists with Van and Vnb (as well as with the other voltages).

Not if one understands the physical reality.

I have work scheduled for today and tonight. Plumbing and studying programming online when I take a break. This is such a great quote, I could spend a year replying to it. There are so many true and false paradigms it either is a source of concern and inquiry or it is not. It is no surprise stumbling into one.

My open wye example creates a third phase by reversing the voltages relative to the other phases. It is a simple thing and should not be over-looked.

No. It is an attempt to clarify for those who can look beyond what they have mistakenly accepted as a complete picture.

 

[mivey]

As for "ridiculous statements about member's abilities and qualifications" is seems that the opposition can dish it out but not take it.

Fortunately, we aren't always bound by other's limitations or shortcomings.

You may not agree with my position and aren't obligated to. But it is clearly substantiated by the definitions I have used as I have used them. Since you haven't accepted or submitted any, you aren't actually in the position to debate anyway.

To the best of my recollection, I posted quite a few.

 

[mivey]

Yes, but the disagreement is over the description of what causes this phase shift. It is equal or equivalent to a 180 deg phase shift. But it is not caused by a phase shift. It is caused by reversing the leads relative to the winding turn direction. The transformer itself is homogeneous, the connection causes the difference.

It is also the connection that causes a phase shift in a 3-phase to 2-phase transformer bank.

In this case you combine sources that do have a time shifted phase difference, caused by their origin at the generator and carried through the system.

The shifts are caused by manipulating the connections, not time.

Again the sources available for combination do have a phase shift that is carried through the system, two cores with two phase displaced fluxes.

Look again. The shift was caused by taking voltages in a winding direction opposite to the directions for the other phases.

Most likely the transformer has overlapping windings sharing a uniform single flux. I believe you are referring to possible differences in current flow in the secondary windings which would have a flux difference equivalence. The difference would be caused by the difference in the current flow between the windings and not by differences in the shared flux. The windings share the same flux but can have different loads and different current flows.

Then they can exhibit a difference and are not simply mirror images on either side of the neutral. It is not simply a matter of what goes on in one side of the winding being a simple inversion of what goes on in the other side. With some uses, it becomes evident that there are two phases present.

I have work scheduled for today and tonight. Plumbing and studying programming online when I take a break. This is such a great quote, I could spend a year replying to it. There are so many true and false paradigms it either is a source of concern and inquiry or it is not. It is no surprise stumbling into one.

Then take your time and try to understand what I was saying. Vab is not dependent on our summing Van and Vnb or subtracting Vbn from Van.

Likewise, in my wye example V5n is not dependent on us summing V56 and V12. By looking at the voltages present in the windings, we recognize that we can connect the transformer as shown to create V5n. We use the fact that the sum of V56 and V12 equals the V5n value of V@120? that we are missing.

With the connection as shown, we have many voltages available for the taking. For example, we have our classic set of 240/120 with the voltages V21 (V@0?) and V43 (V@0?). We also have the V12 (V@180?) and V34 (V@180?) voltages. We also have the V12 (V@180?) and V43 (V@0?) voltages.

Note that the V43 voltage (same phase angle as V21) is our V@0? voltage in the 3-phase set but also note that V12 voltage (V@180? and the reverse of V21) is used in the same 3-phase set as part of the V@120? voltage. And "as part of" I mean the winding of course and that we are using the winding in the opposite direction to that of the other winding half.

Once we have our transformer connections configured, V5n is available as a voltage. But just because V5n is equal to the sum of V56 and V12 does not mean that V65 and V21 are not also available voltages. All of these voltages physically exist with the transformer configured like it is.

So it is the physical manipulation that made V5n available, not a time shift. We normally refer to this as manipulating the voltages, summing the voltages, subtracting the voltages, etc. but hopefully you will understand what is meant. In reality, V12 and V21 and V56 and V65 are going to be there regardless of how we manipulate the connections. The transformer configuration made the previously unavailable V@120? voltage available as V5n.

The single-phase transformer has V@0? and V@180? and 2V@0? and 2V@180? voltages available with the windings in series. Our configuration can make the 2V voltage avilable or not but it will not change the fact that V@0? and V@180? are both physically there.

I could also walk through the Scott T connection and show you that it is the physical manipulation, not time manipulation, that gives us the phase-shifted voltages.

I could also show you the delta-wye connections that have a 30? phase shift or a 210? phase shift. The difference in the phase shifts is taking voltages in a different direction through the windings. So indeed, a different direction does give us a shift in phase. Not a time shift but a physical shift. That is the way transformer connections work.


I'll post my wye example again here so you don't have to look for it and the terminal number references I made:

 

[rattus]

Doesn't matter:

Doesn't matter:

Doesn't matter how the phase shifts are created, One definition of phase is:

phase = (wt + phi0) where phi0 is the phase constant.

If we observe two phase constants, then by definition we have two phases although they are provided by a single phase service.

 

[mivey]

Doesn't matter how the phase shifts are created

Of course not. But Dan appeared to be thinking that somehow using series addition was a validation of a particular version of "physical reality".

I am trying to get Dan away from thinking in a "series addition" manner. By series addition thinking, I mean thinking like:

"To get 240@0? volts the windings are in series so the physical reality is that the 240@0? is the sum of 120@0? and 120@0?, not the difference of 120@0? and 120@180?"

and make him realize that the physical reality is that all of the voltages co-exist and that summing does not mean some of the voltages do not agree with "physical reality".


So Dan,

In my open wye example, we have several voltages available. The "series addition" thinking would say:

"To get 240@0? volts the windings are in series so the physical reality is that the 240@0? is the sum of 120@0? and 120@0?, not the difference of 120@0? and 120@180?. What we really have is V21 + V43 = 120@0? + 120@0? = 240@0?. So in the first winding, the physical reality says the voltage is 120@0? not 120@180?"

Using that same "series addition" thinking, we also have:

"To get 120@120? volts the windings are in series so the physical reality is that the 120@120? is the sum of 120@180? and 120@60?, not the difference of 120@60? and 120@0?. What we really have is V12 + V56 = 120@180? + 120@60? = 120@120?. So in the first winding, the physical reality says the voltage is 120@180? not 120@0?"

So now we have "physical reality" using "series addition" thinking saying two different things. So which is it: 120@0? or 120@180?? We have a 120@120? voltage, which we all know is a real voltage with a 120? phase relationship with the other two voltages. We also know this created voltage has polarity dots on the windings that are opposite to the polarity dots for the windings of the other two voltages.

The reality is that both voltages exist and we can take either one. The fact that the series sum of in-phase smaller voltages equals a larger voltage does not mean that we do not also have smaller voltages that are phase-opposed. There is nothing illegitimate about taking a potential difference. Both of these voltages co-exist and they agree with the physical reality.

These type phase shifts that are caused by physical manipulations is simply the way transformer connections work. These phase shifts, while not time shifts, are the physical realities we get from transformer connections. Sometimes, as I have demonstrated, taking voltages from windings in different directions sometimes gives us the phase shift we are looking for.

 

[Rick Christopherson]

........ with "physical reality".

You're at it again. I left this discussion because of the dishonesty in debating techniques that at least two of you employ. When this topic comes up, you deflect away from it, you trivialize it, you do what ever it takes to avoid it, but then you keep reverting back to it. And now you're emphasizing it.

There is a physical reality and there is a mathematical reality, but you are trying to put forth your mathematical reality as though it was physical reality. You can't have a phase shift without a time shift in the physical world, only the mathematical world. You claim to understand this as it applies to audio signals, but then immediately deny it as it applies to electrical signals...well, what do you think audio signals are comprised of, marshmallows? It's electricity. The same rules apply to both. Do you think transformer theory gets tossed out the window when we talk about one versus the other? No!

You are using a legitimate mathematical transformation, but then trying to defend it as though it was a physical transformation. Stick to your mathematical transformation and all would be fine. But it would be really nice and really helpful if we could carry on an honest debate following proper debating etiquette.

 

[Besoeker]

Bes, I see three sets of sine waves, all with periods of 2π, all beginning at t₀=0 with three different φ₀: ωt+0, ωt+π/3 and ωt+2π/3. Can’t you see that?

There are six:

1. Vmsin(ωt)
2. Vmsin(ωt+π/3)
3. Vmsin(ωt+2π/3)
4. Vmsin(ωt+π)
5. Vmsin(ωt+4π/3)
6. Vmsin(ωt+5π/3)

All different.

 

[mivey]

You're at it again. I left this discussion because of the dishonesty in debating techniques that at least two of you employ. When this topic comes up, you deflect away from it, you trivialize it, you do what ever it takes to avoid it, but then you keep reverting back to it. And now you're emphasizing it.

There is a physical reality and there is a mathematical reality, but you are trying to put forth your mathematical reality as though it was physical reality. You can't have a phase shift without a time shift in the physical world, only the mathematical world. You claim to understand this as it applies to audio signals, but then immediately deny it as it applies to electrical signals...well, what do you think audio signals are comprised of, marshmallows? It's electricity. The same rules apply to both. Do you think transformer theory gets tossed out the window when we talk about one versus the other? No!

You are using a legitimate mathematical transformation, but then trying to defend it as though it was a physical transformation. Stick to your mathematical transformation and all would be fine. But it would be really nice and really helpful if we could carry on an honest debate following proper debating etiquette.

Since, according to you, you do not understand what I'm talking about, you have no basis for debating what I'm talking about. If you do not understand what I'm saying (and based on your own admission as well as your responses, you do not understand), you will be arguing against what YOU think I am saying. You might as well be thrashing about at the wind. By all means go right ahead, but don't expect me to participate in your argument with yourself.