Why is residential wiring known as single phase?

[mivey]

I have not, nor have any others, claimed a voltage does not exist. In the post you quoted, I specifically said these voltages may be used. To make this inference in a reply directed specifically to me is a demonstration of the steps you take to obfuscate the discussion.

You had just finished saying in #2281 that the voltages had to be identical. I say there are also two phase opposed voltages and phase opposed does not mean identical.

 

[mivey]

Obfuscation at its best. Again you post examples that have nothing to do with the core discussion, and are not usually even points of contention. Most of the participants have been trying to focus this discussion to the sinusoidal waveform(s) associated with 120/240V single phase, and particularly the inversion or shift of Vbn based simply on a reference point change.

Why direct that at me? I was responding to gar and RC's posts about sawtooth waves.

 

[rattus]

Inversion and Phase Shift:

Inversion and Phase Shift:

For those who claim that inversion merely changes polarity and does not produce a phase shift, difference, displacement, or whatever, consider this.

Let one wave be sin(wt); phase is (wt)

then the inverted wave is [-sin(wt)]

And, through the magic of trig identities,

[-sin(wt)] = sin(wt + PI); phase is (wt + PI)

Two waves, two phases!

 

[Rick Christopherson]

For those who claim that inversion merely changes polarity and does not produce a phase shift, difference, displacement, or whatever, consider this.

Let one wave be sin(wt); phase is (wt)

then the inverted wave is [-sin(wt)]

And, through the magic of trig identities,

[-sin(wt)] = sin(wt + PI); phase is (wt + PI)

Two waves, two phases!

Which is mathematics. You are trying to argue "real versus mathematical" by using mathematics, and that is a circular argument. I'm not disputing the mathematics.

 

[rattus]

Which is mathematics. You are trying to argue "real versus mathematical" by using mathematics, and that is a circular argument. I'm not disputing the mathematics.

No, I am simply demonstrating that inversion of a sine wave is tantamount to a phase shift of PI radians. No mention of anything else.

 

[Rick Christopherson]

As for real: The phase shifts by inversion are just as real as the other transformer phase shifts. There is no difference from the delta-wye 30? or 210? shifts because they are not time shifts either. Same for the shift from the Scott, open-wye to 4-wire wye, and other connections.

For me to go along with your terminology, you would also have to denounce the other transformer shifts as being real phase shifts. In the past you have stated they were real shifts. I will never agree with you on that basis because it is not consistent.

No, these are real phase shifts. The waveforms are physically shifted in time. The rotor in the generation plant does not reach each winding in the stator at the same time.

The transformer phase shifts/displacements/differences are widely recognized and called to be phase shifts and that is not going to change: that ship has sailed.

You're examples of common convention do not address the differences between real and mathematical phase shifts. This is no different that how common convention addresses the direction of current flow. Common convention states that it flows from positive to negative potentials, but the real electron flow is from negative to positive. Convention is fine when you know and understand when it applies and when it does not. If you used common convention for current flow when analyzing solid state semiconductor materials, it would fail because the operation of those materials is dependent on knowing the actual directions that electrons and holes are biased toward.

 

[Rick Christopherson]

No, I am simply demonstrating that inversion of a sine wave is tantamount to a phase shift of PI radians. No mention of anything else.

"Tantamount", as in "apparent, as in "mathematical". This is fine. However, you have been quoted on the record as stating that it is "real". That is the contention.

 

[rattus]

"Tantamount", as in "apparent, as in "mathematical". This is fine. However, you have been quoted on the record as stating that it is "real". That is the contention.

Much ado about nothing!

 

[Rick Christopherson]

Much ado about nothing!

If it's "nothing", then why do you continue to refuse to retract your statements that brought it up in the first place? It's not that difficult to do. You just type the words out on your keyboard. Simple, huh?

 

[rattus]

If it's "nothing", then why do you continue to refuse to retract your statements that brought it up in the first place? It's not that difficult to do. You just type the words out on your keyboard. Simple, huh?

I don't even know what you are talking about.

 

[Rick Christopherson]

I don't even know what you are talking about.

At the risk of getting myself moderated, I am going to call B.S. here. You know full well what you said because I have specifically quoted all three of you in a single post (and reposted at least once) with examples from each of you. You even commented on these postings. So when you claim to not know, you are lying about it.

Even scanning through 2300 posts looking for my own avatar is time consuming, but I did locate one of the postings where I quoted the three of you in post #1636.

Again, at the risk of bringing a moderator down on me; you are (in my personal opinion), the most dishonest person I have ever encountered on this forum. You will use whatever dishonest tactic you can to make your point. Truth be damned. That's why I say it would be so refreshing to have an honest debate on this topic.

 

[Besoeker]

How so?

Are the two functions discussed periodic?
Do they have the same period P?
Do they have the same origin arbitrary, t₀?
Do they have the same the same t/P as they advance from t₀?

Let's look at your definition again:

The fractional part t/P of the period P through which ? has advanced relative to an arbitrary origin.

That fractional part is different for all six voltages.
Your own definition precludes any of them being the same phase as any other.

Ad nauseam, here are the six expressions again:

Vmsin(ωt)
Vmsin(ωt+π/3)
Vmsin(ωt+2π/3)
Vmsin(ωt+π)
Vmsin(ωt+4π/3)
Vmsin(ωt+5π/3)

The +π/3 etc. is that advance, And different in each of the six cases.

Now, a question for you.
Why does the hexaphase SCR rectifier require six pulses per cycle if it doesn't have six phases?

 

[Besoeker]

Even scanning through 2300 posts looking for my own avatar is time consuming, but I did locate one of the postings where I quoted the three of you in

You did. And you had a pop at me for posting that it's what happens in real life.
I have presented diagrams, drawings and actual pictures of what I have designed and manufactured. In real life.
No dishonesty involved. None whatsoever.
Don't you think, if I design and make this stuff and have been doing so for decades, I just might have a slight inkling of the physics and mathematics involved?

 

[rattus]

At the risk of getting myself moderated, I am going to call B.S. here. You know full well what you said because I have specifically quoted all three of you in a single post (and reposted at least once) with examples from each of you. You even commented on these postings. So when you claim to not know, you are lying about it.

Even scanning through 2300 posts looking for my own avatar is time consuming, but I did locate one of the postings where I quoted the three of you in post #1636.

Again, at the risk of bringing a moderator down on me; you are (in my personal opinion), the most dishonest person I have ever encountered on this forum. You will use whatever dishonest tactic you can to make your point. Truth be damned. That's why I say it would be so refreshing to have an honest debate on this topic.

Frankly, in my few remaining years, I refuse to be bothered by such pettiness.

 

[jim dungar]

But you said H1/X1 relationship which is not a node at all.

I am waiting for your written reference that says I cannot use the relationship of H1 and Xi to use when I arbitrarily assign directions ot my phasors.

Of course, if there is no neutral, one cannot do that.

What do you then?

Now, are you still claiming a sine wave and its inverse are of the same phase??

YES, for 120/240V center tapped transformers.
When you use a equality, like Van = Vnb = -VBN, you are saying the three waveforms are identical.
If the voltages are not equal then you have different waveforms.

What ever happened to the discussion that magintude and phase were independent?


Darn - I forgot to make sure what definition of phase you were using when you asked your question.

 

[jim dungar]

You had just finished saying in #2281 that the voltages had to be identical. I say there are also two phase opposed voltages and phase opposed does not mean identical.

Seriously, try reading all of the words in my post.

I said "if the voltages are identical".

 

[jim dungar]

For those who claim that inversion merely changes polarity and does not produce a phase shift, difference, displacement, or whatever, consider this.

Let one wave be sin(wt); phase is (wt)

then the inverted wave is [-sin(wt)]

And, through the magic of trig identities,

[-sin(wt)] = sin(wt + PI); phase is (wt + PI)

Please don't stop there with your magical trig identities.

Go a few more steps.
sin(wt) = [-sin(wt+PI)]
sin(wt) = [sin (wt+PI+PI)]
sin (wt) = sin(wt+2PI): phase is (wt)

One wave, one phase!

 

[rattus]

I am waiting for your written reference that says I cannot use the relationship of H1 and Xi to use when I arbitrarily assign directions ot my phasors.

You know of course I was referring to electrical nodes. Don't play word games.

What do you then?

Anything you want.

YES, for 120/240V center tapped transformers.
When you use a equality, like Van = Vnb = -VBN, you are saying the three waveforms are identical.
If the voltages are not equal then you have different waveforms.

None of these voltages are inverses. sin(wt) and -sin(wt) are inverses. Van and Vbn are inverses.

What ever happened to the discussion that magintude and phase were independent?

Who ever said otherwise? Magnitude is a constant, always positive. Phase is a function of time.

Darn - I forgot to make sure what definition of phase you were using when you asked your question.

They are all equivalent, but I like the one that clearly states that phase is the argument of the sine function, whatever it my describe.

 

[rattus]

Please don't stop there with your magical trig identities.

Go a few more steps.
sin(wt) = [-sin(wt+PI)]
sin(wt) = [sin (wt+PI+PI)]
sin (wt) = sin(wt+2PI): phase is (wt)

One wave, one phase!

So what? The first one is all I need to prove my point.

 

[gar]

120318-1012 EDT

Rick:

In post 2306 you said

No, these are real phase shifts. The waveforms are physically shifted in time. The rotor in the generation plant does not reach each winding in the stator at the same time.

I would not treat the phase difference of voltage between different displaced windings on the same generator as time displacements, but you can if you want by defining your perspective.

In this generator application I would ask the question how do the waveforms relate to each other at one specific point in time, and from this derive the phase difference. I believe this is what mivey is describing.

It is quite common to treat (study) wave motion at different places at a specific point in time, or alternatively ask what happens at a specific place as time varies. Study what Robertson has to say in Physical Optics.

I see no reason to distinguish between real or physical vs theoretical and mathematical when the theoretical is a good predictor of the physical item. So an equivalent circuit for a voltage source that consists of an ideal voltage source and a single equivalent series impedance is more than adequate for many problems. From this I am satisfied that I can get sufficiently good results in analyzing a real normal center tapped secondary power supply by use of two ideal voltage sources and their equivalent series impedances.

.