Why is residential wiring known as single phase?

[jim dungar]

This displacement was obtained by using identical generators but simply rotating the shaft of one 180? relative to the other.

Sorry but just more purposful misinformation.
You physically created two independent time shifted voltages, which is not the same as the same as a single center-tapped output.

If you cannot create a center-tapped generator output then I guess it was a waste of time asking for the plot.

I have repeatedly refused to participate in discussions of sources other than a center-tap.

 

[rattus]

Sorry but just more purposful misinformation.
You physically created two independent time shifted voltages, which is not the same as the same as a single center-tapped output.

I don't think anyone can tell the difference, so why make a big deal out of it? In other words, who cares?

 

[mivey]

Sorry but just more purposful misinformation.
You physically created two independent time shifted voltages, which is not the same as the same as a single center-tapped output.

If you cannot create a center-tapped generator output then I guess it was a waste of time asking for the plot.

Just more purposeful misunderstanding. As I have said numerous times, the source from the right side of my example was from a center-tapped generator output. It is the source you have at the standard residential service. The purpose of the generators was to show that the phase-displaced voltages occupy the same physical space as the in-phase voltages.

The phase-opposed voltages from the left are connected to the in-phase voltages from the right. The fact that they both share the same space is proof that it is not an either/or condition but simple fact that you can physically have both in-phase and phase-opposed voltages at the output of the center-tap transformer.

I have repeatedly refused to participate in discussions of sources other than a center-tap.

Ignoring the facts will not make them become fiction.

 

[Besoeker]

They are in phase. Just like I have repeated in the past.

It is the way your circuit is wired, not the phasing of the voltages.

Here's a reminder of that circuit:

The first thing to note is that the transformer is configured exactly as it would be for a residential system.
Ia and Ib flow at different times. That different time is during the respective positive half cycles of the voltages that drives them.
It thus follows that the positive halves of the voltage waveforms that drive Ia and Ib occur at different times.

Since they occur at different times, the voltages cannot be in phase. And if they are not in phase...........

As an addendum:

I've taken out the SCRs and made the two halves drive resistive loads.
The voltages and thus currents still have the same relationship they did with the SCRs.
All the SCRs do is prevent the currents flowing during a part of the cycle. They don't change the phase relationships of either current or voltage.

 

[Besoeker]

I have repeatedly refused to participate in discussions of sources other than a center-tap.

This from an earlier post of yours:

#966

Per standard industry practices, as we previously discussed the terminals on these winding are X1, X2 and X3, X4.
I am trying to to not get caught up with directions so I am trying to avoid the "-" sign, so with your permission I will use "~" instead,
and thus list the windings as X1~X2 and X3~X4.

Without knowing anything else about the transformer, except the simple the fact the windings can be paralleled, then we should say the voltage and current relationships of winding X1~X2 are equal to those of X3~X4?

 

[ggunn]

Tesla is spinning in his grave at precisely 60.00Hz. Put some magnets around him and he'll generate enough power to supply a small town.

 

[rattus]

A few rules of life:

A few rules of life:

You can't throw a potato chip.

You can't bend a cracker.

Phasors and vectors are different.

A sine wave and its inverse cannot be of the same phase.

 

[ggunn]

Your comment that: (I said this was a semantic argument)

The difference is pragmatic for the reasons I gave in post #2411.

But all this posturing and slinging around of testosterone is all about what you call it and how you describe it mathematically, not about what it does. No one is disagreeing over what happens when you actually connect up to that center tapped transformer and use the power. That looks like semantics to me, and therefore is not an argument that can ever be settled. This is an eternal flamewar.

 

[rattus]

I know what I'll do. I will draw my phasors in the same direction.

120Vrms@PI L2---------->N---------->L1 120Vrms@0

Are V1n and V2n in phase? Of the same phase?

Well no. Because the phase angles on L1 and L2 did not change. Whattya know? The voltages are separated in time by half a period--PI radians. One is the inverse of the other.

I don't much like the diagram above, although it is correct, so I will change it to this:

120Vrms@PI L2<----------N---------->L1 120Vrms@0

Now the phasor labeling agrees with the node voltages. Good reason to draw the phasors tail to tail, just as is done in a wye. Still no change in the node voltages though. Still out of phase.

 

[rattus]

But all this posturing and slinging around of testosterone is all about what you call it and how you describe it mathematically, not about what it does. No one is disagreeing over what happens when you actually connect up to that center tapped transformer and use the power. That looks like semantics to me, and therefore is not an argument that can ever be settled. This is an eternal flamewar.

Not really. The crux of the matter is that some debaters won't admit that a split phase system creates two phases from a single phase service, and further claim that the voltages seen on L1 and L2 carry the same phase. It is more than semantics.

 

[iwire]

Not really. The crux of the matter is that some debaters won't admit that a split phase system creates two phases from a single phase service, and further claim that the voltages seen on L1 and L2 carry the same phase. It is more than semantics.

It sure seems like a testosterone driven semantics fest.

 

[mivey]

It sure seems like a testosterone driven semantics fest.

Discourse without passion is a stale symphony.

 

[rattus]

It sure seems like a testosterone driven semantics fest.

It is a search for the TRVTH!

 

[ggunn]

Not really. The crux of the matter is that some debaters won't admit that a split phase system creates two phases from a single phase service, and further claim that the voltages seen on L1 and L2 carry the same phase. It is more than semantics.

I beg to differ. No one is arguing that an inverse waveform from Van does not manifest itself at Vbn; this tempest in a teapot is all over whether you call them the same phase or not, and neither side is absolutely right or wrong. It makes not a whit of difference from an applications perspective. We all know and agree on how to wire a house.

What we have here: http://xkcd.com/386/

 

[Fulthrotl]

But all this posturing and slinging around of testosterone is all about what you call it and how you describe it mathematically, not about what it does. No one is disagreeing over what happens when you actually connect up to that center tapped transformer and use the power. That looks like semantics to me, and therefore is not an argument that can ever be settled. This is an eternal flamewar.

my wife, who is subject to succinct and pithy comments from time to time,
looked over my shoulder at this, and commented while leaving the room:

"looks like a bunch of guys trying to determine the direction of flaccid vectors.
they all seem to be pointing due south to me."

not making this up, just reporting facts.

 

[ggunn]

my wife, who is subject to succinct and pithy comments from time to time,
looked over my shoulder at this, and commented while leaving the room:

"looks like a bunch of guys trying to determine the direction of flaccid vectors.
they all seem to be pointing due south to me."

not making this up, just reporting facts.

I'm going to use that one.

 

[rattus]

Misleading??
It must have been a tough assignment, I have no idea how you arrived at 360V.

If the voltages can be combined to produce a higher voltage, than by the virtue of mathematics then one of them should be able to be subtracted from the higher value without providing a misleading answer.
If you don't like your answer maybe the problem is your methodology and not the question?

Here let me do the simple phasor manipulation for you.
Van+Vnb=2Vab
2Vab = 240V@0?|-------------------->
Van = 120V@0?|--------->
2Vab-Van =120V@?? this requires the phasors to be connected tail to tail or head to head
So |--------------------> -|---------> = |--------->---------> = --------- I'll let you put in the direction.

Now
Van-Vbn=2Vab
2Vab = 240V@0?|-------------------->
2Van = 120V@0?|--------->
2Vab-Van =120V@?? this requires the phasors to be connected tail to tail or head to head
So |--------------------> -|---------> = |--------->---------> = --------- I'll let you put in the direction.

Do your your phasors differ?
Why?

They differ by a factor of two:

Van + Vnb = Vab = 240V NE 2Vab = 480V

This error is carried through the rest of the post so I won't bother to comment further.

I prefer to write:

Vab = Van - Vbn = 240V

Because the phasor magnitude and phase are also the node voltage magnitude and phase.

 

[rattus]

I beg to differ. No one is arguing that an inverse waveform from Van does not manifest itself at Vbn; this tempest in a teapot is all over whether you call them the same phase or not, and neither side is absolutely right or wrong. It makes not a whit of difference from an applications perspective. We all know and agree on how to wire a house.

What we have here: http://xkcd.com/386/

But they are NOT of the same phase because phase is precisely defined, and the two waves do not meet the criteria of 'in phase' or 'same phase'. Absolutely!

 

[ggunn]

But they are NOT of the same phase because phase is precisely defined, and the two waves do not meet the criteria of 'in phase' or 'same phase'. Absolutely!

And you are correct within the frame of reference through which you choose to look at it, which is not absolute. For the record, I never took one side or the other on this stupid non-issue. I have been following it strictly for entertainment value, which is wearing pretty thin.

 

[Besoeker]

But all this posturing and slinging around of testosterone is all about what you call it and how you describe it mathematically, not about what it does.

I am talking about what it does. Hence the diagrams, waveforms, detail from actual drawings, and photographs of how my designs have been implemented. In real life.
The controlled rectifier circuit I have shown a few times would not work the way it does unless you have different phases for each SCR.
That's just pragmatic reality.

I know what works and how it works and have to understand phase relationships. If I didn't, I couldn't produce designs that work. But I have.
In short, others may have talked the talk.
I've walked the walk.

I don't need to "win".
If anyone has gained even a little from what I have posted, that's prize enough.