Why is residential wiring known as single phase?

[mivey]

...For the residential issue, only AB or BA presents a common reference (1). AN, BN, NB, NA exclude other portions of the coil that we wish to test. Therefore those references cannot establish synchronization or phase.

??? If that is true then how do you suppose we establish the phase relationships for three phase circuits where the coils are separate? I appreciate the effort but you've built the rest of the argument on a faulty foundation so you will have to try again a different way.

 

[mivey]

No matter how much, um, discussion folks have about what is a phase, where do you measure it, etc, as far as I can tell, we call it "single phase" because it that's the best name for it.

I am not voting for changing the name, just for people to understand why the name is not a comprehensive system description but simply a label we use.

 

[mivey]

:thumbsup:

But this does beg the question: is there an 'actual' or is everything an 'appearance'?
To co-opt Descartes: "quodammodo ergo sum"?hmy:

That is an astute observation. My contention has been that both methods are relying on assumptions. As for the use, it would not be such a noticeable thing except for the fact that the words "appear" are only being used when discussing one method and excluded for the other. That makes the use of "appear" not so "harmless" (I can't think of the word I want at the moment).

 

[mivey]

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.

To do that you have to say that Vmax = -Vmax. The two equations did not reduce to the same thing.

 

[mivey]

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

The one-sided use of the term sure makes it seem that way.

(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.)

Then it appears you & I are just not in agreement on terminology. It would appear we agree on the physics.

 

[rbalex]

To do that you have to say that Vmax = -Vmax. The two equations did not reduce to the same thing.

No I don't. I only have to establish that the phase value of the voltage functions is the same. Which I have demonstrated many ways, many times. Although no one seems to have noticed it until recently.

In my original entry into this morass I said, "...phase is not an electrical concept; it has nothing to do with Volts, Amps, polarity, amplitude, Ohm?s Law, Kirchhoff?s Laws, Ampere?s Law, Lenz?s Law, Coulomb?s Law, or any other ?law? derivable from Maxwell?s equations." - It's MATH.

Write the voltage function correctly for ANY arbitray set of points you desire and, for a properly installed residential 120/240V system, the phase value for each and every voltage function will ultimately resolve to Φ(t)= wt+Φ. It's simple trig/algebra.

 

[jim dungar]

...it would not be such a noticeable thing except for the fact that the words "appear" are only being used when discussing one method and excluded for the other. ....

I might have listed Group 1 as "single phase 120V = (2) 'out of phase' voltages that appear 'in phase' when the neutral is not the reference point" but I honestly do not recall Group 1 ever taking this position.

Could it be because the out of phase waveforms only exist if the neutral is the reference for the o-scope?

 

[rbalex]

No I don't. I only have to establish that the phase value of the voltage functions is the same. Which I have demonstrated many ways, many times. Although no one seems to have noticed it until recently.

In my original entry into this morass I said, "...phase is not an electrical concept; it has nothing to do with Volts, Amps, polarity, amplitude, Ohm?s Law, Kirchhoff?s Laws, Ampere?s Law, Lenz?s Law, Coulomb?s Law, or any other ?law? derivable from Maxwell?s equations." - It's MATH.

Write the voltage function correctly for ANY arbitray set of points you desire and, for a properly installed residential 120/240V system, the phase value for each and every voltage function will ultimately resolve to Φ(t)= wt+Φ. It's simple trig/algebra.

BTW this is consistent with "classic" two-phase systems where there will be two characteristic phase values: wt+Φ, wt+Φ +90^o and conventional three-phase systems where the characteristic phase values can ultimately be resolved to: wt+Φ, wt+Φ+60^o and wt+Φ+120^o.

 

[rattus]

I'm tired

I'm tired

Can anyone justify the argument that describing a waveform as either an inverse or being shifted 180 degrees is germane to the OP's question?

Can anyone explain why the fact that V1 and V2 are provided by a single transformer winding has anything to do with the OP's question.

 

[topgone]

Can anyone justify the argument that describing a waveform as either an inverse or being shifted 180 degrees is germane to the OP's question?

Can anyone explain why the fact that V1 and V2 are provided by a single transformer winding has anything to do with the OP's question.

And that's a good question to place all other posts in one perspective! Good points there.

 

[rattus]

BTW this is consistent with "classic" two-phase systems where there will be two characteristic phase values: wt+Φ, wt+Φ +90^o and conventional three-phase systems where the characteristic phase values can ultimately be resolved to: wt+Φ, wt+Φ+60^o and wt+Φ+120^o.

Bob, you sure you don't mean 0, 120, & 240 degrees not volts.

 

[Rick Christopherson]

Can anyone justify the argument that describing a waveform as either an inverse or being shifted 180 degrees is germane to the OP's question?

Can anyone explain why the fact that V1 and V2 are provided by a single transformer winding has anything to do with the OP's question.

You're playing your old games that I have pointed out so many times in the past. You are focusing on a secondary comment in order to detract attention away from the primary comment that stands before you.

We will get to your secondary question soon enough. Please address the primary issue first.

 

[rbalex]

Bob, you sure you don't mean 0, 120, & 240 degrees not volts.

Nope, I meant what I said. I'm discussing the phase value of voltage functions, not the voltage functions themselves.

Φ(t) = wt+Φ+180^o ultimately resoves to -Φ(t) = wt+Φ.
Φ(t) = wt+Φ+240^o ultimately resoves to -Φ(t) = wt+Φ + 60^o and
Φ(t) = wt+Φ+300^o ultimately resoves to -Φ(t) = wt+Φ +120^o.

The characteristic phase values are still wt+Φ, wt+Φ+60^o and wt+Φ+120^o.

Polarity is irrelevant; otherwise conventional Y connections would be "six-phase.".

 

[jim dungar]

Can anyone justify the argument that describing a waveform as either an inverse or being shifted 180 degrees is germane to the OP's question?

Can anyone explain why the fact that V1 and V2 are provided by a single transformer winding has anything to do with the OP's question.

Because they are exactly what was asked about.

Every sparky knows he's working with 2 phases in a standard residential panel, and better not get them mixed up! If I have to be careful with tandem breakers, and not getting my multi-wire legs on the same phase etc., how does "single phase" apply?

Because they pull off opposite ends of the same utility transformer (ie. one winding)? Because they cancel out on the neutral with 240V? Or is it a misnomer. I've always been curious about this.

Notice the question used the word phases.
He then asked about 240V pulled from the two ends of 'one winding'.

And then there was his follow up question:

If the two 120V legs are in phase and additive, how do multiwire circuits work? Isn't a two-hot-single-neutral permissable because the legs cancel (ie. not additive) on that neutral? If they cancel, does this not mean they are opposite phase? Just asking!

This is partly why I came up with the comment about needing to explaining why "out of phase voltages combine to a larger number while out of phase currents combine to a smaller number".

 

[Sierrasparky]

congrats folks, 20 pages over 10,000 views and over 500 replies!:happyno:

 

[gar]

1203209-2000 EST

See http://en.wikipedia.org/wiki/Phase_(waves)

A 180 deg shift is not described as in phase. It is mentioned that this shift is described as antiphase. However, a 360 or N*360 is defined as in phase ( i.e., mod 2Pi ).

.

 

[ronaldrc]

I don't understand why everyone wants to make everything more complex than what it really is?

We don't need to talk about shifting the sine or about zero crossing.

Most on here know you can shift the sine with capacitance or inductors they don't need to be
introduced into this fairly simple electrical concept.

Here is a pictorial of what we are discussing. Please use Ie Explorer to open.

http://home.comcast.net/~ronaldrc/wsb/The_Edison_Neutral.html

And reversed polarity is not the same thing as shifting a sine wave in time.

 

[gar]

120209-2142 EST

If you have two voltage sources of the same amplitude and frequency, then if they are in phase they can be connected in parallel. No big sparks, tripped breakers, etc. This is what you do in paralleling generators. The generators have to be correctly phased to be paralleled. If they are 180 deg out of phase, then when paralleled there are real BIG problems.


ronaldrc:

What happens when in your second drawing X1 is connected to X4 (paralleling the two voltage sources)? Are those sources in phase or out of phase?

.

 

[Hv&Lv]

congrats folks, 20 pages over 10,000 views and over 500 replies!:happyno:

Yea, looks like iwire was right!! only a few more to go...

There are two ways to handle this.

For me I just accept 'because we do'

The other way takes 600 forum posts.


Good luck!

 

[ronaldrc]

120209-2142 EST

If you have two voltage sources of the same amplitude and frequency, then if they are in phase they can be connected in parallel. No big sparks, tripped breakers, etc. This is what you do in paralleling generators. The generators have to be correctly phased to be paralleled. If they are 180 deg out of phase, then when paralleled there are real BIG problems.


ronaldrc:

What happens when in your second drawing X1 is connected to X4 (paralleling the two voltage sources)? Are those sources in phase or out of phase?

.

Gar

I assume you are talking about when we change to a 3 wire edison neutral circuit.

Thats like shorting line #1 to line #2 it would let the smoke out.

But it not because there different phases. I don't really understand your question.