Why is residential wiring known as single phase?

[rattus]

And where does the -sin(wt) come from. Is it because the leads are reversed relative to the other windings turn direction or is it caused by the magic voltage genie?

No mention of transformer in the last 2300+ posts ... That's hilarious.

Think math man; think math!

I will take your reply to mean you can't prove they are in phase either.

 

[__dan]

Think math man; think math!

I will take your reply to mean you can't prove they are in phase either.

There are two windings that are identical and in phase.

I will take your reply to mean that you cannot prove otherwise.

 

[rattus]

There are two windings that are identical and in phase.

I will take your reply to mean that you cannot prove otherwise.

Don't drag transformers into my question. It is mathematical only!

 

[david luchini]

No it is not correct, because the resultant phasor is indeterminate. It could be pointing to the right, or to the left. That's why tail-to-tail is never used for vector subtraction. It's a pipe dream that Rattus dreamed up.

Nonsense. The resultant phasor is only indeterminate if you don't understand phasor combinations. But Jim (not Rattus) explained it very succinctly in post #1999:

Maybe you need to read up on phasors just like your advice to anyone who disagrees with you.

In a tail-to-point configuration we ADD the phasors together.
In a tail-to-tail or a point-point configuration we SUBTRACT them.

So here is your tail-to-tail vector problem. Which vector represents the correct answer, C or D?

View attachment 6640

"Which vector represents the correct answer, C or D?" is a silly question since you didn't ask which vector you wanted to subtract from which. So the correct answer will obviously be both are correct. D=A-B, and C=B-A.

Just as in the transformer example with tail-to-tail vectors of 120<0 and 120<180, would the correct answer of the combination of the two vectors be 240<0 or 240<180? Both are correct depending on which vector is subtracted from which. 120<0-120<180=240<0 and 120<180-120<0=240<180.

 

[__dan]

Don't drag transformers into my question. It is mathematical only!

Math is knowing how to set up the problem. How do you normalize for the reversal of the leads relative to the other winding's turn direction? By forgetting the other voltage is the other winding? And forgetting that winding is identical and occupies the same time, same space, same core as the first winding? By resorting to magic?, The voltage genie?

 

[Rick Christopherson]

Don't drag transformers into my question. It is mathematical only!

Well we already covered the "pure mathematics" answer earlier today, but you ran away from the discussion before it was finished. "Every mathematical manipulation must result in indentical results." So neither argument can be proven nor disproven mathematically. So why do you continue to ask others to disprove what you cannot prove?

 

[rattus]

Math is knowing how to set up the problem. How do you normalize for the reversal of the leads relative to the other winding's turn direction? By forgetting the other voltage is the other winding? And forgetting that winding is identical and occupies the same time, same space, same core as the first winding? By resorting to magic?, The voltage genie?

''

There is pure math and applied math. My question is pure math.

I must assume you don't get that distinction.

 

[Rick Christopherson]

"Which vector represents the correct answer, C or D?" is a silly question since you didn't ask which vector you wanted to subtract from which. So the correct answer will obviously be both are correct. D=A-B, and C=B-A.

Ding, ding, ding...give the barbie a kewpie doll. It was intended to be a silly question to reveal the silliness of claiming that two vectors tail-to-tail automatically represented subtraction, as Rattus previously claimed. You don't throw two vectors tail-to-tail and claim subtraction, because you have no idea which one subtracts from the other.

 

[rattus]

Well we already covered the "pure mathematics" answer earlier today, but you ran away from the discussion before it was finished. "Every mathematical manipulation must result in indentical results." So neither argument can be proven nor disproven mathematically. So why do you continue to ask others to disprove what you cannot prove?

So far, no one has offered to answer the question.

Maybe you could answer it and put an end to this nonsense.

 

[Rick Christopherson]

Well we already covered the "pure mathematics" answer earlier today, but you ran away from the discussion before it was finished. "Every mathematical manipulation must result in indentical results." So neither argument can be proven nor disproven mathematically. So why do you continue to ask others to disprove what you cannot prove?

So far, no one has offered to answer the question.

Maybe you could answer it and put an end to this nonsense.

I believe the answer was already given. The nonsense is that you keep asking ad nauseum, with the deception that since no one can disprove it then it must be proven. You can neither prove it nor disprove it, so why do you insist on asking? I suppose we can add voodoo logic to your repertoire of voodoo math, huh?

 

[Besoeker]

In my mind, inversion is not the same as 180 degree phase shift, although I stipulate that for an infinitely repeating pure sine wave the difference between the two is purely semantic.

Disagree.
The difference is a quite pragmatic one.
Without that difference, you wouldn't get 240V end to end and that does matter to an electrician wiring a house.
And the rectifier circuit I posted wouldn't work as it does without that difference.

 

[Besoeker]

You keep bringing this circuit up, and it takes every ounce of personal control I have to not lash out and call you an idiot for doing so. Doing it once, is an oversight. Continually doing it, well that posses a challenge to politeness.

You present this circuit as though it becomes functional only because you analyze it a certain way. Therefore, all other methods of analysis cause this circuit to fail. That's not the way circuits work.

As was stated earlier "Every mathematical manipulation must result in indentical results." So for you to claim that your circuit functions solely because you have chosen to analyze it using a phase shift is short-sighted and logically flawed. The circuit doesn't function solely because you analyze it based on a central reference point. It will continue to function just the same regardless which point(s) you choose for your analysis.

It isn't an analysis. It's what happens in real life. Been there. Done that. Got the T-shirt.
So, how about you control your choleric temperament and just explain why two firing pulses per cycle are required to control the operation of the circuit if there is only one phase at work?

 

[Besoeker]

No mention of transformer in the last 2300+ posts ... That's hilarious.

Um......well.......

Not just mentioned but also drawn. A number of times.
#63, #119, #227, #2331, #2339, #2363
are just a few of those posts.

 

[jim dungar]

So here is your tail-to-tail vector problem. Which vector represents the correct answer, C or D?

View attachment 6640

The correct answer cannot be determined until after the subtraction operation has occurred.
Technically all phasors should always have a positive magnitude with their angles being 'inverted' as needed, after all a line cannot truly have a negative length.
Mathematically it makes no difference, so this convention is usually reserved until the final step.

This is why I have said we do not really 'generate' a negative AC voltage, so if we calculate one, we have simply assigned it the wrong direction.
Van=Vnb=-Vna=-Vbn for a single center-tapped winding.

 

[pfalcon]

I'm asking again....please read Jim's refresher course on phasor math in post #1999:

I did. Jim overlooked something. Tail-to-tail occurs when one is a resultant phasor. That would be the 240 phasor which cannot exist for rattus.

Rattus' phasor diagram is correct the way he drew it...
He drew two phasors (both positive) connected tail-to-tail. As Jim points out, tail-to-tail phasors would be combined by subtraction:
120@0 - 120@PI = 240@0.
The phasor diagram is correct and the phasor math is correct. I don't see what you are taking issue with.

The diagram is not correct for a basic phasor diagram. Rattus has drawn an origin shifted diagram. The flaw is evident because there's no origin tailed resultant.

A 240 resultant starting at the origin should appear somewhere. Either 120 phasor should be placed at the origin. Then the other phasor can be indicated by subtracting the 120 phasor from the resultant 240 phasor.
No 240 phasor from the origin means a misdrawn diagram.

P.S. Hope you had a good vacation. Counting down to mine in a month. Can't wait.

Excellent and best wishes.

 

[rattus]

I did. Jim overlooked something. Tail-to-tail occurs when one is a resultant phasor. That would be the 240 phasor which cannot exist for rattus.

The diagram is not correct for a basic phasor diagram. Rattus has drawn an origin shifted diagram. The flaw is evident because there's no origin tailed resultant.

A 240 resultant starting at the origin should appear somewhere. Either 120 phasor should be placed at the origin. Then the other phasor can be indicated by subtracting the 120 phasor from the resultant 240 phasor.
No 240 phasor from the origin means a misdrawn diagram.

Maybe you would like to show us the correct way to draw the diagram??

 

[ggunn]

Yes. You actually understood how vectors work, which was the whole point in the first place. You performed the proper vector addition. It is Ratuss' "Voodoo Vectors" that don't follow proper vector math that I was pointing out.

Sorry for the response. You accidentally stepped into the middle of Rattus' "voodoo math" without realizing it.

I thought I smelled something. I'd better wipe my feet before I go in the house.

 

[ggunn]

Disagree.
The difference is a quite pragmatic one.
Without that difference, you wouldn't get 240V end to end and that does matter to an electrician wiring a house.
And the rectifier circuit I posted wouldn't work as it does without that difference.

To which point do you disagree? That they are different or that it makes no difference that they are different? Man, that's convoluted...

 

[ggunn]

Gar;

Your analysis subdivides the wave in time. The time division example uses the same reference point for time but uses a different, opposite reference point relative to the winding turn direction, which is homogeneous on the same core. A salient fact to omit.

Take the instantaneous case and subdivide the winding, not the waveform. This analysis yields the fact that a measurement between any two points on the winding is a perfect fractal of the whole, an exact copy that differs only in amplitude. As you state above, any two points on the winding are "in phase". Voltage and current are instantaneous between any two points on the winding or between any three points, or between any infinte sample and combination of points on the winding. The phase does not shift, there is no propagation delay from one part of the winding to the other, in the scale of time used for practical applications, the effect is instantaneous with no time delay.

It is confusing to claim or instruct otherwise.

Thanks. I thought I was the only one trying to make the point that since what happens on the primary happens (virtually) instantaneously and simultaneously on A and B, there can be no phase shift between A and B.

 

[jumper]

At this point I am seeing visions of WWI in my head.