Why is residential wiring known as single phase?

[pfalcon]

Group 4 (me apparently): phase is not an electrical phenomenon; it is an applied mathematics concept. As long as the derived voltage functions [V(t)] with respect to time have the same phase value [φ(t) = t + φ₀], the functions are "in phase." They may not be in synchronism (all values the same at all times) but they are ?in phase.?

All values the same at all times would refer to magnitude not synchronization.

 

[pfalcon]

With no amplifiers to confuse the issue we apply a sine wave from a single voltage source simultaneously to both sets of deflection plates the result is a Lissajous figure of a single straight line at 45 deg to horizontal. If the phasing of the signal to one set of plates is inverted (phase shift of 180 deg), then the angle of the straight line changes by 90 deg.

You should mention here that with an AC signal you can make an apparent shift in phase by reversing the polarity of the leads.

 

[jim dungar]

Because there is a little more to it than basic electrical circuitry. Group #2 is correct in one respect in that the forces in the transformer are physically acting in the same direction for normal loads. But that view is limited in scope and does not give a complete picture. I do agree with part of what they are saying, and I understand why they hold to that view, but I also see that there is a broader picture not covered by the standard labels.

Actually I see Group 2 regularly using words like 'appear' and 'seem', thereby acknowledging there is a bigger picture. Which is why I made it part of my gross simplification definition.

 

[pfalcon]

No, we are not saying N must be used. We are saying that it is convenient and logical to do so, ...

Are you saying my methodology is not logical or convenient? ...

Yep, that's what he said. Not convenient or logical because it might produce results he can't explain.

 

[pfalcon]

Group 4 (me apparently): phase is not an electrical phenomenon; it is an applied mathematics concept. As long as the derived voltage functions [V(t)] with respect to time have the same phase value [φ(t) = t + φ₀], the functions are "in phase." They may not be in synchronism (all values the same at all times) but they are ?in phase.?

In order to properly test the phase they need to establish their time (synchronization). Properly this would be established off the secondary winding as a whole. Thereby A or B.
Second they need to establish the "forward" direction for time. On an AC circuit we normally pick a zero crossing when the second reference point (N or B) is rising.
That procedure establishes the base phase and direction of the system.

Other portions of the circuit are then tested against that reference setup by maintaining the time base.
Synchronizing is easy as virtually any point can be used.
Maintaining the "forward" direction requires the leads be in the same physical order on the winding. This they rebel against and measure "backwards".

 

[mivey]

But it does not make a difference using my methodology. When I do my analysis, negative voltages and negative currents, tell me I have made some incorrect assumptions in regards to assigning directions.

I have no problem with your methodology and is one I use also. It is a tool just like the other method.

What I take issue with is the position of some that one method deals with real voltages and the other deals with what "appears" to be voltages. The fact is that the voltages exist for both configurations and BOTH methods require that the user make an assumption about direction.

Forget the word "phase" for a moment: Do you not agree that the forces available from X1/X2 and X3/X4 can be used as positive forces in different directions that produce results that occur at different times?

 

[rattus]

It's not nitpicking. You made a very specific and absolute statement, and it goes to the core of this discussion.

If it is just nitpicking, then you would have no problem retracting the statement, correct?

And, just how does this go to the core of the discussion?

 

[rbalex]

I looked back through and my notes were correct. The problem is that you have moved part of the phase component and let it reside outside the sinusoidal expression (i.e., the negative sign).

Clearly, the original expression [2] Vmax sin (t + φ) is not the same as what I will call your revised expression [2] Vmax sin (t + φ ? 180?).

You can't conclude that the original [2] shifted by 180? degrees is just one equivalent expression ?Vmax sin (t + φ). What you really have is expression [2] shifted by 180? is -[2], like we would expect.

Vmax sin (t + φ) does not equal Vmax sin (t + φ ? 180?)
Vmax sin (t + φ ? 180?) does not equal ?Vmax sin (t + φ)

I think you got caught in a round-a-bout.

Fair enough, the Cosine of ? 180? is always -1. The phase value [φ(t) = t + φ] is still the same which is what defines phase.

 

[mivey]

Following the reasoning of the NEC, is there really a reason to define words that are commonly used.:roll:

Based on thousands of posts and multiple threads here, I will have to say: yes

For the vast majority of the time, there is no problem. But we need to understand the phraseology we use is rarely absolute, therefore when a question arises, we should switch to using very specific phraseology, maybe even including a definition or reference, and make no assumption the other person is 'speaking the same language'.

Much easier to do in a setting different than what we have here.

The one thing I wish was taught with more emphasis is that; adjectives are important.

What kind of adjectives?

 

[rbalex]

All values the same at all times would refer to magnitude not synchronization.

Why? What does synchronize mean, but "at the same time."

 

[Rick Christopherson]

And, just how does this go to the core of the discussion?

Well, if it doesn't go to the core of this discussion, and it is just trivial and nitpicking, then why won't you retract the original statement?

If it is just nitpicking something trivial, then you should have no problem retracting the original statement, right?

So just retract it.

 

[mivey]

Actually I see Group 2 regularly using words like 'appear' and 'seem', thereby acknowledging there is a bigger picture. Which is why I made it part of my gross simplification definition.

And that is an issue. There is not one "real" picture with all the other pictures being "fake" as the use of words like "appear" and "seem" indicate.

 

[mivey]

This they rebel against and measure "backwards".

I would contend that measuring from Earth is not "backwards" but fairly standard. This measurement point would normally be associated with the center tap of the single-phase transformer. Positive voltage direction is an assumption we make, not something dictated by the materials, manufacturer labels, physics, etc.

 

[mivey]

Fair enough, the Cosine of ? 180? is always -1. The phase value [φ(t) = t + φ] is still the same which is what defines phase.

Sure, if that is what you use, but you are using two different phase terms, [φ(t) = t + φ] and [φ(t) = t + φ +180?], and trying to say they are one and the same. They are not.

 

[rattus]

And why do you call it stupid? Unless of course you already know what you'll see and don't want to acknowledge it. And that would be that your definition of phase has nothing to do with electricity, just your eyeballs.

Yes, I already know what to expect, and I know how to use a scope, and I understand the basics of transformers, and I see no reason to move my reference point to demonstrate what I already know. That would be useless. I know too that phase is sometimes loosely applied to L1 and L2. I know also that the fact that V1 and V2 are taken from a common winding is irrelevant. I know that phase angles only apply to the fundamental frequency of a wave, therefore an inversion is tantamount to a phase shift. Anything else I should know? Oh yes, the ubiquitous residential service is single phase.

 

[rattus]

Well, if it doesn't go to the core of this discussion, and it is just trivial and nitpicking, then why won't you retract the original statement?

If it is just nitpicking something trivial, then you should have no problem retracting the original statement, right?

So just retract it.

Answer the question please.

 

[Rick Christopherson]

And that is an issue. There is not one "real" picture with all the other pictures being "fake" as the use of words like "appear" and "seem" indicate.

I would agree with this, with the exception of the word, "Fake". No one has deemed anything to be "fake".

However, words do carry far more meaning than many posters here assume. I'm sure that most people that are relatively familiar with the NEC are aware of the distinction between the words "will" and "shall". These words are legally defined and used with specific intent. "Will" is not an absolute word, but "shall" is absolute. Your State ordinances don't say, "...a driver will come to a complete stop at a stop sign....". They say, "...a driver shall come to a complete stop at a stop sign...". There is a significant distinction, in what otherwise looks trivial.

The same is true with the word "are". It is correct to say V1n and Vn1 "are" inverses. It is not correct to say V1n and Vn1 "are" out of phase. They "are" inverses, or they "appear" out of phase. (By the way, you did successfully give an example with your coupled generator, where it would be correct to say that those voltages "are" out of phase, and "appear" to be inverses. However, that example is not the same as the topic at-hand.)

 

[Rick Christopherson]

Answer the question please.

I didn't see your posting while I was writing post #537. However, that doesn't change the discussion you and I were having. You claimed I was nitpicking trivial things. My question preceded yours, and you danced around it. If it is just trivial nitpicking, then why won't you retract it?

It is my belief that you know it is not trivial nitpicking, and you know it does go to the core of this discussion. You won't retract it because you know just how significant the words truly are. It is my opinion (not an accusation) that you use these words for deliberate deception.

If words such as these were not used, I would not be engaged in this discussion. I have no interest in deciding which method a person chooses to use. I do, however, care about misinformation. That is the only thing I contend in this discussion.

 

[rbalex]

Sure, if that is what you use, but you are using two different phase terms, [φ(t) = t + φ] and [φ(t) = t + φ +180?], and trying to say they are one and the same. They are not.

I am saying they resolve to having the same phase value [φ(t) = t + φ] and that is what defines phase.

I offered a consistent mathematical reference (Post #132) to what defines phase; I didn't have to make it up or create a new set of terms to explain it or describe what phases do or how to measure them. I'm only saying what a phase is. It doesn't rely on any specific means of measurements other than correctly stating the function's period [t] and origin [φ] and it is the only "scientific" explanation consistent with the OP's question, "Why is residential wiring known as single phase?" - because the voltages only have a single phase value - no matter how you measure it.

 

[rattus]

I didn't see your posting while I was writing post #537. However, that doesn't change the discussion you and I were having. You claimed I was nitpicking trivial things. My question preceded yours, and you danced around it. If it is just trivial nitpicking, then why won't you retract it?

It is my belief that you know it is not trivial nitpicking, and you know it does go to the core of this discussion. You won't retract it because you know just how significant the words truly are. It is my opinion (not an accusation) that you use these words for deliberate deception.

If words such as these were not used, I would not be engaged in this discussion. I have no interest in deciding which method a person chooses to use. I do, however, care about misinformation. That is the only thing I contend in this discussion.

Rick can't explain how his nit-picking is germane the OP's question? Can anyone else explain it?