Why is residential wiring known as single phase?

[mivey]

No Mivey, you have never answered the question. You've dodged it. I never said anything about a "time shift". The three of you keep saying that the phase shift is "real" not "mathematical".

If not a "time shift" then what? Perhaps a clearer definition of what you are calling a shift. I thought maybe you mean the difference in phase as a shift. Then I thought you meant the time shift as a phase shift. If neither of those, then exactly what are you meaning? I'm really trying to see where you are coming from.

The question was posed to identify which side of zero the noise anomaly would appear.

If it is a physical phase shift, as the three of you keep claiming, then it must appear in the positive half cycle of both secondary waveforms. It can only appear in the negative half cycle if one of them is simply an inversion. Your mathematical equality sin(wt + 180) = -sin(wt) removes the minus sign, so you can't have it in the negative half cycle if it is a phase shift. There is no minus sign if it is a "real" phase shift.

You don't get an argument from me until you claim it is a "real" phase shift, and not an inversion that is mathematically made to appear as a phase shift.

Given your description, I would have to say at this point that what you are calling a phase shift is not there. Nobody has shifted the voltages like you are thinking (at least the way it appears you are using "shift"). They are there just like they always were. The 0? voltage was there as well as the 180? voltage.

Nevertheless, you have still dodged the question. Which side of zero will you see the noise anomaly? (Rattus has)

The other side of course. I don't think anyone has said differently about the type noise you are describing.

 

[mivey]

When you say it is "real," that's physical. When you deny that it is a mathematical equality, that makes it physical. It's not a real phase shift. It is mathematical.

I think he is saying the voltage was not shifted, physically or mathematically. For example, Van was at 0? and Vbn was at 180?. No one has "shifted" the voltages. They remain as they were before. And Vnb was at 0? in that example. Nobody took Vbn=V<180? and shifted it to Vbn=V<0?.

 

[jim dungar]

? Even so, I have no disagreement with the general statement that the "windings are in phase" if they can be paralleled without the fireworks. What we mean is that the voltages are in phase. Let's call that an absolute based on the physical.

? That however is not the only truth that is present. There is also the truth that if the windings are connected in fireworks mode that the voltages are not connected in phase. Let's call that another absolute based on the physical.

Except to get to this condition the connections must be physically changed from the first example.

To me I see the absolute is; the actual physical arrangement makes a difference.

? I believe you are proposing that if X1-X2 can be paralleled with X3-X4 then they are connected in phase. I agree with that. It would seem your next logical statement would be that if X1-X2 and X3-X4 are in phase when paralleled then they must be in phase when in series like we see with X1-X2&X3-X4. I would also agree with that. I don't think any of us here are disputing how transformers are connected and how they work.

? What I have said is that while it is a real-world fact that X1-X2 is in phase with X3-X4, another real-world fact also exists and that fact is that X1-X2 is not in phase with X4-X3.

Change the actual connections get different results.

? Both are facts and both are based on the fact that the conditions of "in phase" or "not in phase" are relative

They are relative to the actual connections.

And the shocking lesson that there is more than one truth. So I guess since it really is that simple then you would agree that we have these two physical truths:
1) The voltage from X1 to X2 and the voltage from X3 to X4 have a 0? displacement between them
2) The voltage from X2 to X1 and the voltage from X3 to X4 have a 180? displacement between them

I think everyone has agreed that V12=-V21. This is a simple mathematical conversion

[quote= jim dungar ]
What an absolutely positively absurd argument; Yeah but if they were connected differently we would get different results.

Absurb if that was actually my argument. [/quote]
I'll requote you so you don't have to scroll up.

? that the "windings are in phase" if they can be paralleled without the fireworks. What we mean is that the voltages are in phase?

? if the windings are connected in fireworks mode that the voltages are not connected in phase.

Based on your responses, my argument would be that you haven't really looked at my graphic ?

Your graphic, in post 847 shows two sources on the left side of a center-tapped transformer feeding a single winding on the right hand side, which is also listed as a source. This is not a standard 120/240V connection.

But let us ignore that minor detail. You show a current as flowing out of node A at the same time one is flowing into node B effectively we could call these currents Ia and Ib. If your currents and your voltages are in-phase with each other (based on the resistive load) why is Ib not flowing out?

By the way the current paths you show are exactly what I would predict using industry standard transformer connections of into X1 and out X4.

But they are not what David posted in #156 when he was solving a previous question

? reference current as Ia leaving the source at A, Ib leaving the source at B?.

 

[Besoeker]

It works by inversion that is mathematically represented as a phase shift. But you're dodging the question.

It isn't mathematically represented.
It's what happens in real life.
It's real.

 

[mivey]

Except to get to this condition the connections must be physically changed from the first example.

To me I see the absolute is; the actual physical arrangement makes a difference.

Whether we have the voltages in
X1->X2/X3->X4 or
X1/X2->X3/X4 or
X3->X4/X1->X2 or
X4->X3/X2->X1 or
X4/X3->X2/X1 or
X2->X1/X4->X3 or

does not change the fact that the X1->X2 voltage is in phase with the X3->X4 voltage and the fact that the X1->X2 voltage is opposite in phase to the X3->X4 voltage.

Change the actual connections get different results.

What connections have to be changed to make both Van and Vnb have a 0? difference as well as Van and Vbn have a 180? difference? Why do you think we have to change the connections inside the transformer?

I'll requote you so you don't have to scroll up.

That demonstrates that both voltages exist, not that we have to change the internal transformer connections to use those voltages.

Your graphic, in post 847 shows two sources on the left side of a center-tapped transformer feeding a single winding on the right hand side, which is also listed as a source. This is not a standard 120/240V connection.

The two generators serve to show that we can have two 180? physically displaced voltages supplying a load. From the right side, we have the standard center-tapped transformer fed by a 2-wire primary. The left side source (made up of the 180? labeled generator-supplied voltages) is paralleled with the right side source (made up of voltages from a standard single-phase transformer).

This is not a standard 120/240V connection. But let us ignore that minor detail.

Nothing to ignore. The transformer on the right is a standard single-phase transformer fed from a single-phase source coming from the right. That is about as standard as it gets.

You show a current as flowing out of node A at the same time one is flowing into node B effectively we could call these currents Ia and Ib. If your currents and your voltages are in-phase with each other (based on the resistive load) why is Ib not flowing out?

Because of my whole point that the directions are relative. Look at the generator on the left. Using the normal reference, we can see that the currents are indeed flowing in those directions. It is also a physical fact that the two generators are identical except that one is physically rotated 180? relative to the other. V_A and V_B do indeed have a 180? displacement.

By the way the current paths you show are exactly what I would predict using industry standard transformer connections of into X1 and out X4.

That is a good thing since I do not disagree with that. It is the assignment of the positive direction that we disagree on. As my graphic shows, that is arbitrary and either way is valid and both agree with the physical reality.

But they are not what David posted in #156 when he was solving a previous question

Did not really follow that line of conversation in detail. As I recall, I wasn't paying much attention that argument but I thought it was an argument about "the sum of currents into a node equals zero" vs "the sum of currents entering a node equals the sum of currents leaving a node" so pretty much skimmed over it. Did I miss something?

 

[Rick Christopherson]

If not a "time shift" then what? Perhaps a clearer definition of what you are calling a shift. I thought maybe you mean the difference in phase as a shift. Then I thought you meant the time shift as a phase shift. If neither of those, then exactly what are you meaning? I'm really trying to see where you are coming from.

Fair enough. I am not actually focusing on the phase shift itself. I am focusing on the inversion that we mathematically equate to a phase shift. The equality sin(wt+180) = -sin(wt) converts the minus sign into a phase shift. Therefore, there is no minus sign on the left side of the equation. Without this minus sign, there can't be an inversion, only a phase shift.

My example of the noise in the positive peak of the primary showing up in both positive and negative peaks of the secondary reveals that one of the two wave forms is an inversion of the other. If it were a true phase shift (no minus sign), then the noise would show up in both positive peaks of the two wave forms. I wasn't specifying "when" it would have to show up. Only that without a minus sign, it would have to be present in the positive peak somewhere.

Given your description, I would have to say at this point that what you are calling a phase shift is not there. Nobody has shifted the voltages like you are thinking (at least the way it appears you are using "shift"). They are there just like they always were. The 0? voltage was there as well as the 180? voltage.

The other side of course. I don't think anyone has said differently about the type noise you are describing.

If you agree that the noise would be present in the negative half cycle, then you must agree that there is an inversion present, would you not? I do not contest the usage of the equality that an inversion can be represented as a phase shift. What I do contest is when the three of you say that the phase is not just apparent, but actually real.

The reason why this discussion exists and persists is because so many people have heard you (plural) say that the phase shift is real and absolute, when in fact, it is only an apparent phase shift.

P.S. My apologies. I was pulled away while writing this response, so I have not read any of the new responses that came in during the past 2 hours (or however long it has been).

 

[Rick Christopherson]

It isn't mathematically represented.
It's what happens in real life.
It's real.

Besoeker, yours is one of the postings that came in while I was pulled away. This is exactly the point I make. Sorry to duplicate what I wrote above, but if this was a "real" phase shift, then the noise I mentioned previously would show up in both wave forms on the positive peak. The phase shift is a mathematical equality, not an actual quality. That is why the noise shows up in both the positive and negative half cycles.

Edited to add: The inversion is "real". The phase shift is "apparent".

 

[Besoeker]

if this was a "real" phase shift, then the noise I mentioned previously would show up in both wave forms on the positive peak. .

It would show up at the same point in time.

 

[Rick Christopherson]

It would show up at the same point in time.

Yes, that is an obvious consequence. Which is why it cannot be a "real" phase shift, but instead a "real" inversion that can be viewed as an "apparent" phase shift.

I don't contest anyone's usage of an apparent phase shift in evaluating a system. I do contest when it is called a "real" phase shift. This example shows that it is not real, but apparent.

Edit: If the phase shift was real, it would phase shift the noise too.

 

[rbalex]

But, (wt) NE (wt + 180)

Wasn't in HS, wasn't in college algebra, wasn't in college trig, wasn't in analytic geometry, wasn't in calculus, wasn't in DE.... Maybe in the "new math" which I never had.

Still don't see how the minus sign disappears. Maybe it's just "apparent", that is, not really there?

Maybe in Boolean algebra, huh?

I haven't said wt = (wt + 180). But remember you were the one that originally stuck the terms in trig functions. You were the one that originally specified HS algebra. I guess I'll have to let gar enlighten you on the significance.

 

[rattus]

Yes, that is an obvious consequence. Which is why it cannot be a "real" phase shift, but instead a "real" inversion that can be viewed as an "apparent" phase shift.

I don't contest anyone's usage of an apparent phase shift in evaluating a system. I do contest when it is called a "real" phase shift. This example shows that it is not real, but apparent.

Edit: If the phase shift was real, it would phase shift the noise too.

The definition of "phase" is silent on the matter of noise.

 

[Rick Christopherson]

The definition of "phase" is silent on the matter of noise.

Well, then I guess that means it doesn't contradict me then, doesn't it?

 

[rattus]

Well, then I guess that means it doesn't contradict me then, doesn't it?

It means that it doesn't matter. It means that other than you, no one cares.

 

[rbalex]

The definition of "phase" is silent on the matter of noise.

Just as it's silent on the matter of magnitude (amplitude) and sign (polarity). But - I thought you were tired of definitions anyway.

 

[Rick Christopherson]

It means that it doesn't matter. It means that other than you, no one cares.

If it is so meaningless to you, then you should have no problem in not calling the phase shift "real". You keep pretending that it is not important, yet you refuse to back away from it either. That doesn't sound like you think it is unimportant, does it?

 

[rattus]

Just as it's silent on the matter of magnitude (amplitude) and sign (polarity). But - I thought you were tired of definitions anyway.

No so! There is mention of zero crossing from negative to positive.

 

[jim dungar]

the fact that the X1->X2 voltage is in phase with the X3->X4 voltage and the fact that the X1->X2 voltage is opposite in phase to the X3->X4 voltage.

Typo?

Why do you think we have to change the connections inside the transformer?

Never said you need to change the transfromer to go from Vnb to Vbn, that can be done with a change in the measurement probes.
Physically changing from X1-X2&X3-X4 to X2-X1&X3-X4, does require a rewiring. Can't you see that in one way has X2 joined to X3 and the other way has X1 connected to X3?

The two generators serve to show that we can have two 180? physically displaced voltages supplying a load. From the right side, we have the standard center-tapped transformer fed by a 2-wire primary. The left side source (made up of the 180? labeled generator-supplied voltages) is paralleled with the right side source (made up of voltages from a standard single-phase transformer).

I guess I missed where I said two independent sources could not be interconnected/ Oh yeah, I have been focusing only on the transformer connections used in millions of installations.

Did not really follow that line of conversation in detail. As I recall, I wasn't paying much attention that argument but I thought it was an argument about "the sum of currents into a node equals zero" vs "the sum of currents entering a node equals the sum of currents leaving a node" so pretty much skimmed over it. Did I miss something?

You are the one who chooses a voltage directions, so I thought it interesting you would show that the voltage across and the current through a resistive load are not consistent.

And I am amazed at how you are insistent that I have tried to 'force a direction' on anyone. I have said that the physical construction makes a difference. Real world winding directions are also extremely important in wye, delta, and T connections.

 

[rattus]

Those equations definitely aren't equal; but when used as the arguments for reduced periodic functions, such as Sine or Cosine, the phases [wt] remain the same.

You just ignored the phase constant. You cannot do that, it is part of the phase definition. There would never be any phase shift without the phase constants.

 

[rbalex]

You just ignored the phase constant. You cannot do that, it is part of the phase definition. There would never be any phase shift without the phase constants.

OK then tell me you accept trig identities.

Edit add: You don't need to necessarily tell me you understand them - although it would be helpful if you did

 

[rattus]

OK then tell me you accept trig identities.

Edit add: You don't need to necessarily tell me you understand them - although it would be helpful if you did

I understand them well enough to know that you can't drop minus signs, and you can't ignore phase angles. Please explain or we will think you are a humbug like the Wizard of Oz.