Why is residential wiring known as single phase?

[Besoeker]

Since, according to you, you do not understand what I'm talking about,

Mivey
Stay on topic please.

 

[Rick Christopherson]

Since, according to you, you do not understand what I'm talking about, you have no basis for debating what I'm talking about.

I never said I didn't understand what you are talking about. Quite the contrary. I do understand it quite well. But you are once again deflecting. That's what I mean by the dishonest debating techniques.

 

[jim dungar]

Obfuscation reigns again.

... are the physical realities we get from transformer connections.

If I may reword: Transformer connection are what they really are. The physical relationship between a transformer's terminals output are based on the reality of its connections.

..... taking voltages from windings in different directions sometimes gives us the phase shift we are looking for.

Echoing back what I got from your wording: The assignment of voltage directions is mathematically equivalent to a phase shift.

Summarizing, what I infer from your wording:
The "physical realities" of of transformer connections can be ignored, it is only the arbitrary assignment of mathematical references that counts.

 

[__dan]

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, ...

No.

In the single phase example, the two secondary windings share the same magnetic flux, the same turn direction, the same time and space. The windings are in series, they physically add.

mathematically V + V = 2V

because of the phasor representation of the voltage and the convention of the midpoint as common, you write:

V - (-V) = 2V, reduced from sin(wt) - sin(wt + 180) = 2sin(wt)

I never disputed that the other polarity was not there. I consistently stated the polarity reversal was not there inside the transformer, the two windings are matched and identical in every way. The reversal of polarity indicated does happen, but it happens at the output by the attachment of the connections to the transfomer.

The description of the physical reality does not include the double negative, it is added by you. Saying I do not believe in the second voltage is also added by you. I have been saying I have both added and subtracted windings to change voltage as needed.

I will say you have some good examples with the tire rotation. The open Y and delta, the windings have sources that are phase displaced and this is carried through the system, available for manipulation by the arrangement of connections. Many different voltages and phase angles can be obtained.

In the single phase example, an infinite variety of connection changes can only yield two different phase angles, 0 and 180, which is the special case of reversal of the leads polarity. All sums add linearly and there is no phase displacement in a second dimension. The 0 to 180 deg rotation is a one dimensional solution on the same line.

 

[gar]

120314-1419 EST

RicK:

What is your definition of "phase shift", and "phase difference"? Are these the same, and if not how do they differ?

Does shift mean to you that it has to result from a time difference?

How would you describe the output of a resolver in relationship to one of its inputs as the shaft is rotated? Do you think this is a time shift in the non-mathematical real world?

If I draw two sine waves of identically the same frequency on the same X-axis, and one is displaced sideways on the X-axis relative to the other, and they are not overlapping, then are they phase shifted relative to the each other? edit add Change the word frequency to period. Where period can be any type of non-time dependent unit.

If I put two 6" scales side by side and offset lengthwise, then are they shifted relative to one another?

.

 

[Rick Christopherson]

120314-1419 EST

RicK:

What is your definition of "phase shift", and "phase difference"? Are these the same, and if not how do they differ?

Contrary to some of the other discussions here, I am not debating what is or is not phase. I am talking about the differences between a mathematical transformation and a physical transformation. Mathematically, an inversion is equivalent to a phase shift, but physically, it is not. You guys keep trying to defend this mathematically, but that aspect is not in question. What none of you have been able to do is defend it physically, and that is the side of the discussion I am contending.

When ever I bring this up, you guys quickly scurry back to claim that you are discussing "ideal" systems....but then a couple of days later, you revert back to calling things "real" and "physical".

If you want to continue to use these terms, then you need to defend them without scurrying back to your Ideal holes.

 

[rattus]

One can observe V12 or V21 and see two phases. Either way, a single load is involved.

One can observe V1n and V2n and see two phases with different loads at the same time.

Since we have defined V1n and V2n relative to N, what we see is what we get, and we see TWO phases. They are both real and one is no more real or important than the other. Once we have an equivalent circuit, we do not burden ourselves with transformer details. That is what Dr. Heizer, RIP, taught us in our AC Circuits course. I don't think much has changed since then.

And Dr. Hansen, RIP, taught us that signs do matter! They are relevant. They must not be ignored! I don't think math has changed much either.

 

[Rick Christopherson]

And Dr. Hansen, RIP, taught us that signs do matter! They are relevant. They must not be ignored! I don't think math has changed much either.

But you are ignoring the sign when you call it a "real" phase shift. The sign is real. The voltage is real. The phase shift is mathematical.

 

[gar]

120314-1536 EDT

Rick:

Your response did not address the questions in my post. Do you even know what a resolver is and how it works? Do you know what an LVDT is and how it works?

.

 

[Rick Christopherson]

120314-1536 EDT

Rick:

Your response did not address the questions in my post. Do you even know what a resolver is and how it works? Do you know what an LVDT is and how it works?

.

Yes, I know what a resolver is. And yes, I know that this is an attempt to deflect from the actual topic. It doesn't apply. I told you that the first two times you brought this up. As I said a few hours ago, it would be really refreshing to have an honest debate without you guys trying to go off on tangents trying to deflect the topic. We're not talking about resolvers or 3-phase systems. We're talking about single-phase, center tapped transformers.

If you can't make your point within the bounds of the original topic, it should be a sign that it is not a very valid point to be making in the first place. Right?

 

[gar]

120314-1610 EDT

Rick:

It is not a deflection.

One needs to have a set of definitions for similar characteristics that are meaningful when viewing different applications. Why should I use different definitions for the same characteristics when I work on optical, mechanical, acoustic, electrical, and mathematical systems?

All vibrational systems have some very common characteristics in both the real and abstract worlds.

.

 

[Rick Christopherson]

It is not a deflection.

First off, your resolver example is the antithesis of what you should be bringing forward in this argument with me, because this does represent a physical phase shift. There is a literal and physical time delay from when the magnetic source excites the individual windings.

Secondly, you are confusing me with someone that is arguing mathematics. The mathematics are correct and not in contention. I am solely arguing about the usage of the terms/words "real", "physical", and their synonyms.

 

[rattus]

But you are ignoring the sign when you call it a "real" phase shift. The sign is real. The voltage is real. The phase shift is mathematical.

Rick, instead of jousting with windmills, why don't give us your opinion on the misuse of trig identities to try to prove an impossible claim.

 

[rbalex]

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

Posted quite a few what; descriptions of the effect of "phases" or definitions of what phase is?

You aren't obligated to accept any of the definitions I use, but at least one is IEEE Std. 100 sourced. You've never once shown how I misapplied it. Your strongest argument has been "Nuhuh - We don't use it that way." I don?t find that particularly compelling.

 

[Rick Christopherson]

Rick, instead of jousting with windmills, why don't give us your opinion on the misuse of trig identities to try to prove an impossible claim.

I am not arguing whether your math is wrong. Your math is fine. That's the whole point.

 

[rattus]

I am not arguing whether your math is wrong. Your math is fine. That's the whole point.

Well am I right or wrong? Is the phase of [-sin(wt + PI)] wt, or is it (wt + PI)?

 

[Rick Christopherson]

That's exactly what I mean by not being able to carry on an honest debate here. When a topic is brought up that you can't contest, you have to deflect it to something else.

 

[gar]

120314-2025 EDT

rbalex:

How is your definition of same phase supported by IEE Std 100?

The standard says nothing about waveform, does not define same phase, and gives no implication that t/P = 0.5 can be classified as the same as t/P = 0. or 1.

One book that I previously referenced --- "Electrical Circuits and Machinery", by Hehre and Harness, on pages 7, and 9, at least --- illustrates 180 degree phase shifts. Page 9 is of a magnetizing current.

.

 

[rattus]

Well am I right or wrong? Is the phase of [-sin(wt + PI)] wt, or is it (wt + PI)?

Rick said my math was fine. I'll take that to mean that he believes the phases of sin(wt) and sin(wt + PI) are different.

Seems to me they have to be!

 

[Rick Christopherson]

It would be very refreshing to have an honest debate without games and deflections.