Why is residential wiring known as single phase?

[jim dungar]

Are I_a and I_b in phase?

Your rectifier circuit prevents Ia and Ib from existing at the same point in time. I posted a diagram showing Ia and Ib in-phase in a non-rectifier circuit.

 

[rbalex]

You can if you wish but how they flow in terms of phase and magnitude is a consequence of of the applied voltage and load characteristics.

I would suggest the transformer secondary voltages are not synchronized because they have opposite polarities as applied, but they share the same phase. That is, their periodic voltage functions, however derived, all have the same period P and at any time t they have simultaneously advanced t/P over their respective period.

Edit add: FWIW, that applies to the fundamental frequencies of Ia and Ib in 1004 too.

 

[rattus]

MORE SNIPERS:

MORE SNIPERS:

Hanging my hat on it? No. It just had a simple explanation which as we say here, was good enough for government work. And saved a lot of typing.
[ur]http://en.wikipedia.org/wiki/Skin_effect[/url]


emphasis added

And the area surrounding the residential wires would be called ... ... INSULATION! Alternating current flows INSIDE the copper to a depth determined by it's frequency. Not outside. Otherwise insulation would be the most worthless material in the world. It would burn/melt as the power passed through it and you'd get shocked/burned just touching it.
:rotflmao:

Maybe you should read some of those materials instead of just collecting them.

SNIPER ATTACK! TAKE COVER NOW!

 

[jim dungar]

No one is saying that V12 and V34 are not in phase. What has been said is that it is also true that V12 and V43 are phase-opposed. My open-wye example shows that usage is physically valid because we make use of a

I think you need to check your circuit diagrams.

A center-tapped/reconnectable set of windings is connected a lot more like delta than it is like a wye.

I ask for a little leeway with standard designations, and ignoring external connections.
Given three transformer coils X1-X2, X3-X4, and X5-6.
A delta connection would be X2&X3, X4&X5, and X6&X1 -an open delta could be just X2&X3
A wye connection would be X2&X4&X6 - an open wye could be just X2&X4

So an open wye is the physical connection of V12+V43, while an open delta is the physical V12+V34, giving two vastly different results.

Besoeker's rectifier does not change the physical connection of V12+V34.

 

[mivey]

And the area surrounding the residential wires would be called ... ... INSULATION! Alternating current flows INSIDE the copper to a depth determined by it's frequency. Not outside. Otherwise insulation would be the most worthless material in the world. It would burn/melt as the power passed through it and you'd get shocked/burned just touching it.

Again, the energy travels in the wave. If you do not understand that then you simply need to get your education up to date. Simple examples of peas pushed through a pipe might be used at a very elementary level but it is not a correct representation of how the energy is transported. Those types of examples can actually cause a stumbling block to a better understanding, much like you are faced with now. Time to get rid of your elementary ideas and graduate to something that is more accurate.

 

[jim dungar]

You can look at it any way you wish Jim, but it is very logical to define both terminal voltages relative to N--in a consistent fashion.

I have never said it is not. In fact I usually do so, in my math.

It would be inconsistent to use more than one reference in a circuit,...

Good luck with 3-wire delta circuit, if this is really your position.

You say tomato, I say tomahto. That's it..

I have never siad you were forced to use any specific pronunciation. But I have argued against discussing produce when the OP was about 'utility transformers' and 120/240V services.


The physical connections of transformer windings have a direct impact on how the real world operates. Please go ahead and physically wire the rectifier circuit as V12 and V43, let me know how that works for you.

 

[Besoeker]

Your rectifier circuit prevents Ia and Ib from existing at the same point in time.

Not so.
The I_a and I_b shown would exist as show at the times they do irrespective of whether there was a rectifying device in the circuit. The rectifiers do not change that timing.

 

[Besoeker]

I would suggest the transformer secondary voltages are not synchronized because they have opposite polarities as applied, but they share the same phase. That is, their periodic voltage functions, however derived, all have the same period P and at any time t they have simultaneously advanced t/P over their respective period.

Edit add: FWIW, that applies to the fundamental frequencies of Ia and Ib in 1004 too.

Are I_a and I_b not opposite phases?

 

[jim dungar]

120224-0925 EST
In my post 1293 you ignored responding to the first and main part of the post.

If we use the conventional usage of the labeling of X1 and X2 being one secondary coil with X2 having an associated dot, and the other other coil being X3 and X4 with 4 having the dot, then connect X1 to X3. What is the voltage difference between X2 and X4? In turn is V_X2-X1 in-phase or 180 degrees out of phase with V_X4-X3?

You have physically moved the winding connections, but the relationship of the voltages, V21 &V43 across the open circuit transformer windings does not change.

You must have missed when I posted a diagram of a similar connection, way back in post #1092, where I connected X2&X4.

 

[rattus]

I would suggest the transformer secondary voltages are not synchronized because they have opposite polarities as applied, but they share the same phase. That is, their periodic voltage functions, however derived, all have the same period P and at any time t they have simultaneously advanced t/P over their respective period.

Are you suggesting that both waveforms have the same phase constant???

I think not.

 

[pfalcon]

No. As I told you before, the power flows towards the load as if the wires were a waveguide. The energy flows along both wires towards the load. It travels in the electromagetic field surrounding the wires, not riding in the wires like a line of coal cars traveling back and forth.

Again, the energy travels in the wave. If you do not understand that then you simply need to get your education up to date. Simple examples of peas pushed through a pipe might be used at a very elementary level but it is not a correct representation of how the energy is transported. Those types of examples can actually cause a stumbling block to a better understanding, much like you are faced with now. Time to get rid of your elementary ideas and graduate to something that is more accurate.

SNIPER ATTACK! TAKE COVER NOW!

Oh please. This is a major technical error on Mivey's part. Are you gonna tell me you think the current travels OUTSIDE the copper as Mivey stated? Pony up Rattus. Is he right or wrong? Should we take a poll? I'll even lead off.

IN) AC travels inside the copper. The frequency is low enough to use the entire copper cross-section in residential wiring. (per PFalcon)
OUT) AC travels outside the copper. The copper acts as a wave guide channeling the current through the electromagnetic field surrounding the wires. (per Mivey)

I vote IN!

 

[rbalex]

Are I_a and I_b not opposite phases?

Nope; they just aren't synchronized either. If you care to do the Fourier analysis; assuming you use the same period P as the transformer's the phase of the fundamental frequencies of I_a and I_b will be the same as the transformer's.

 

[rattus]

I have never said it is not. In fact I usually do so, in my math.

Good luck with 3-wire delta circuit, if this is really your position.

I would ground one corner of the delta (on paper) and call that my reference. Of course there are cases where one would have to make exceptions. Perhaps I should say "insofar as possible." But today, we are discussing single phase systems.

The physical connections of transformer windings have a direct impact on how the real world operates. Please go ahead and physically wire the rectifier circuit as V12 and V43, let me know how that works for you.

X2 tied to X3 would form the common/neutral and it would work just fine. But, we knew that from day one.

 

[rattus]

Oh please. This is a major technical error on Mivey's part. Are you gonna tell me you think the current travels OUTSIDE the copper as Mivey stated? Pony up Rattus. Is he right or wrong? Should we take a poll? I'll even lead off.

Has NOTHING to do with the OP's question. Just more sniping.

 

[jim dungar]

I would ground one corner of the delta (on paper) and call that my reference.

Come on out here, to this part of the real world, where more than 80% of the installed 3-wire deltas are ungrounded.

But today, we are discussing single phase systems.

Actually specific single-phase connections that are used to supply residential 120/240V.

X2 tied to X3 would form the common/neutral and it would work just fine. But, we knew that from day one.

Hmm, great idea, ignore the subscript methodology you have been promoting for designating voltage references. Maybe someday you will maintain some consistency.

 

[rattus]

Come on out here, to this part of the real world, where more than 80% of the installed 3-wire deltas are ungrounded.

I said "on paper". Most if not all simulation programs require a "ground" reference. Quite alright for simulation purposes where we can't get hurt by doing something stupid.

Hmm, great idea, ignore the subscript methodology you have been promoting for designating voltage references. Maybe someday you will maintain some consistency.

What is inconsistent? V1n is seen at X1, neutral is the X1-X2 tie, and V2n is seen at X4. Pretty standard stuff as I see it.

You know that Vx4x3 is 180 out from Vx3x4 and Vx1x2. So what is the problem?

 

[Besoeker]

Nope; they just aren't synchronized either. If you care to do the Fourier analysis; assuming you use the same period P as the transformer's the phase of the fundamental frequencies of I_a and I_b will be the same as the transformer's.

A Fourier series analysis will give you the magnitude of the various harmonics that constitute the waveform.
It's something I routinely have to do to analyse the effects of non-linear loads on supply voltage distortion. When we bid for a project I have to commit to not to exceed levels of distortion. And agree to financial consequences for failure to comply with the limits.
That gets your attention.

 

[pfalcon]

Has NOTHING to do with the OP's question. Just more sniping.

Credibility Rattus. If you don't know where the current is in the conductor then how can you be an expert on its use. His current description invalidates E=IR. If you don't know how current flows in a conductor then how can you claim to understand the current induced in the secondary. Your ad hominem attack on the challenge of a technical error is dropping your credibility. Right now it implies you think residential current travels through the air. If someone can't understand the current stays in the copper then they'll never understand phase.

 

[rbalex]

A Fourier series analysis will give you the magnitude of the various harmonics that constitute the waveform.
It's something I routinely have to do to analyse the effects of non-linear loads on supply voltage distortion. When we bid for a project I have to commit to not to exceed levels of distortion. And agree to financial consequences for failure to comply with the limits.
That gets your attention.

Are you saying the fundamental frequency of the currents in 1004 won't have the same phase as the transformer's?

 

[rattus]

Credibility Rattus. If you don't know where the current is in the conductor then how can you be an expert on its use. His current description invalidates E=IR. If you don't know how current flows in a conductor then how can you claim to understand the current induced in the secondary. Your ad hominem attack on the challenge of a technical error is dropping your credibility. Right now it implies you think residential current travels through the air. If someone can't understand the current stays in the copper then they'll never understand phase.

Nonsense, the phase definition does not specify how the energy flows nor is it necessary to do so. You are just introducing extraneous arguments.

I don't know whether to put on my helmet or my poncho. Maybe I will put on both.