Why is residential wiring known as single phase?

[jcassity]

this should answer you
below, you still have only one source of water no matter how many times you "tap" the source.
you would need three drums of water to have three phase.

If you have a bank account with two debit cards , one for you and the wife, its still one bank account.

In three phase you need three separate coils on the secondary of the transformer (three bank accounts.
In residential applications there is one secondary coil and it is tapped twice with a common N / G.

It would be a lot easier to call it single phase "dual tap" source rather than the misnomer of two phase. Ive yet to physically see two phase

with respect to post 24 and 27, your source is still one drum of water no matter how many times you "TAP" into the source.

if you want another phase, your going to need another drum.

 

[roger]

FWIW, those four-direction covers are often used for event/temporary wiring. I've seen new-looking ones recently, but can't for the life of me remember who makes them.

Those are not covers, they are receptacles called "Quadplex" by Hubbell/Bryant, they are made in 15 and 20 amp residential grade, spec grade, surge suppression, HG, and IG varieties and are still in production, you can see them in Hubbell or Bryants online catalogs


Roger

 

[K8MHZ]

Those are not covers, they are receptacles called "Quadplex" by Hubbell/Bryant, they are made in 15 and 20 amp residential grade, spec grade, surge suppression, HG, and IG varieties and are still in production, you can see them in Hubbell or Bryants online catalogs


Roger

Cool!

I looked one up and it was made of plastic. The one in my pic, I am pretty sure, is made of metal. Think about metal prongs through slots in a metal plate. Maybe it just looked like it was metal. The next time I go there I will check.

 

[ActionDave]

back to the op's question, do you agree with my illustration and agree post 24 & 27 pretty much summed it up?

No. You have to give the formula that proves it.

 

[rattus]

this should answer you
below, you still have only one source of water no matter how many times you "tap" the source.
you would need three drums of water to have three phase.

If you have a bank account with two debit cards , one for you and the wife, its still one bank account.

In three phase you need three separate coils on the secondary of the transformer (three bank accounts.
In residential applications there is one secondary coil and it is tapped twice with a common N / G.

It would be a lot easier to call it single phase "dual tap" source rather than the misnomer of two phase. Ive yet to physically see two phase

You need to reverse the arrow on one leg or the other.

 

[JPMacG]

This thread is hilarious. I love it!

If I place my dual-trace oscilloscope probe grounds on electrical ground and place one probe on one hot and the other probe on the other hot then the two waveforms that show on the oscilloscope are 180 degrees out of phase.

So in this sense there are two phases.

Why don't you all admit that the terminology is just convention and stop this silly discussion?

 

[rbalex]

Cool!

I looked one up and it was made of plastic. The one in my pic, I am pretty sure, is made of metal. Think about metal prongs through slots in a metal plate. Maybe it just looked like it was metal. The next time I go there I will check.

Yeah, but unless their "ground-up" side is on the right, the faceplates' "phase rotation" is wrong. (JK; that statement is just as ridiculous as most of this thread; but it uses phase about as correctly)

 

[gar]

120212-1318 EST

K8MHZ:

With reference to your post 673 you will have to answer your own question.

If you think the voltages at X1 and X4 are "in phase", then put a "crowbar" between them and measure the current.

"Crowbar" is a slang term used for a low resistance path, and overvoltage crowbar devices have been used on critical DC power supplies. One example is an SCR triggered when the output voltage exceeds some threshold. The output remains shorted until power is removed.

.

 

[mivey]

No - I'm not. I'm saying the characteristic function of the phase value reduces to the same - which it does; sign being irrelevant to establish phase.

Something you have completely made up and not supported by the math. Even the source you referenced does not agree with what you are saying. It can't because it is not mathematically sound.

My explanation is consistent with why we call conventional systems, "single-phase,""two-phase," and "three-phase."

There is no justification in forcing a fit using bad math.

Those designations have been around longer than either of us and there was a better reason than, "Well, we gotta call it something."(edit add: the post 2 answer) It even applies to the currently discussed "six-phase" system where the phase value elements are reducible to six - 30? increments.

Your "theory" is not supported by historical math. You may think it is, and you may want it to be, but if you will consult any decent physics text dealing with the math of oscillatory systems you will find you are wrong.

You are trying to say two different phase constants, that are shifted relative to each other can be made to be the same thing. Until the signal completes a full cycle, it is not repeating itself and it is not going to be the same. The scenario you have is for two waveforms with different initial conditions. With different initial conditions, the phase constant is different and the two phases are different.

As I stated before, all you have demonstrated is that you can shift two waveforms and you can get them to be in phase. We already know that.

To make a physical illustration, consider two equal springs oscillating back and forth at the same frequency. You are saying that a spring in the far right position and starting to move left is in phase with a spring that is in the far left position and starting to move right. The math says the phases are different. The physics say the phases are different. Your "PhD reference" says the phases are different. You, however, choose to say they are the same.

It is a free country and you can choose to make up whatever math you want. I respectfully reject your "new" math.

 

[gar]

120212-1716 EST

rattus questioned my 60 deg figure in post 668. This should have been 30 deg. This is basically the shift in a delta to Y transformation.

If you pick a primary line-to-line phase at a delta primary as the reference, then relative to that reference look at a Y line-to-neutral voltage you will see a 30 degree shift or N*120 added to 30. And you can add a 180 shift by flipping the scope leads. Note: to run the experiment with a scope you should use some potential transformers or other isolating means. This potential transformer part of the comment is for those that want play with the phasing to an oscilloscope as has been shown in some previous posts and not burn up the probe ground leads.

The above error is why I need others to question my statements and calculations. The concept, brain, and keyboard are not always very well connected.

.

 

[rbalex]

Something you have completely made up and not supported by the math. Even the source you referenced does not agree with what you are saying. It can't because it is not mathematically sound.

There is no justification in forcing a fit using bad math.

Your "theory" is not supported by historical math. You may think it is, and you may want it to be, but if you will consult any decent physics text dealing with the math of oscillatory systems you will find you are wrong.

You are trying to say two different phase constants, that are shifted relative to each other can be made to be the same thing. Until the signal completes a full cycle, it is not repeating itself and it is not going to be the same. The scenario you have is for two waveforms with different initial conditions. With different initial conditions, the phase constant is different and the two phases are different.

As I stated before, all you have demonstrated is that you can shift two waveforms and you can get them to be in phase. We already know that.

To make a physical illustration, consider two equal springs oscillating back and forth at the same frequency. You are saying that a spring in the far right position and starting to move left is in phase with a spring that is in the far left position and starting to move right. The math says the phases are different. The physics say the phases are different. Your "PhD reference" says the phases are different. You, however, choose to say they are the same.

It is a free country and you can choose to make up whatever math you want. I respectfully reject your "new" math.

Rather than simply link to it, I will quote the definition. For clarity, I will make one editorial adjustment to separate the definition from the example.

Phase:
The angular position of a quantity.

For example, the phase of a function cos(ωt + φ₀) as a function of time is φ(t)= (ω t + φ₀)

φ(t)= (ωt + φ₀) is indeed a linear function; however, the expression [ωt + φ₀] is used as the argument of a periodic function in the example.

Although cosines would work just as well, since the debates have been about Sine rather than Cosine functions, I have simply used the trigonometric identity:

sin(u?v) = sin(u)cos(v) ? cos(u) sin(v)
​

In an earlier post, I acknowledged a benign error indicating cos(? 180?) = ?1 (It is always -1).

When the element ?u? in the periodic function is [ω t + φ₀] and the element ?v? in the function is[ 180?] then:

sin([ω t + φ₀]? [180?]) = sin([ω t + φ₀]cos([ 180?])? cos([ω t + φ₀]) sin([180?])

= sin([ω t + φ₀]x(-1)) ?cos ([ω t + φ₀]x(0))
=- sin([ω t + φ₀])​

The phase of the reduced function is still [ω t + φ₀]

Unless you that insist sign is an element of the definition of phase (which I acknowledge many erroneously have) my math is not even particularly difficult, let alone "new."

 

[rbalex]

Please forgive me, I thought I had already discussed your spring analogy with you before.

Yes, I do beleive they are in phase; I don't beleive they are in synchronysim. Certainly things that ae synchronized are in phase, but the reverse isn?t necessarily true. I find it intertesting that some of the debaters are willing to give up amplitude,('cause their scope and scaling factors says so) but insist polarity is a requirement of phase.

 

[jcassity]

This thread is hilarious. I love it!

If I place my dual-trace oscilloscope probe grounds on electrical ground and place one probe on one hot and the other probe on the other hot then the two waveforms that show on the oscilloscope are 180 degrees out of phase.

So in this sense there are two phases.

Why don't you all admit that the terminology is just convention and stop this silly discussion?

I knew this was coming, thank you!!! it enhances the mystery

What you are saying is equal to saying a single pole double throw relay is mechanically designed with no difference to a single pole single throw relay and that we need to call them both DPDT,, thats not correct.

somebody somewhere was told to wind a single conductor with two ends sticking out and then told to weld in a center tap to offer a reference ground.

I still see it being a single phase of winding but the tap offers two lower but equal voltages.

I like your scope example though, in reality and for calculations purposes in kw load or figuring out hvac demands on equipment, i do sometimes have to treat this as two phase although we call it single.

the trouble is there are single phase 120 and single phase 240 devices both being wired unlike one another yet we still call them both "single phase".

 

[rattus]

sin([ω t + φ₀]? [180?]) = sin([ω t + φ₀]cos([ 180?])? cos([ω t + φ₀]) sin([180?])

= sin([ω t + φ₀]x(-1)) ?cos ([ω t + φ₀]x(0))
=- sin([ω t + φ₀])​

The phase of the reduced function is still [ω t + φ₀]

The trig identity is correct, but it seems to me that if we lose the "phi0",

then,

V1n = 170(sin(wt))

and,

V2n = 170(sin(wt +/- 180))

The phase shift is 180 degrees. That is they are 180 degrees out of phase.

 

[rattus]

120212-1716 EST

rattus questioned my 60 deg figure in post 668. This should have been 30 deg. This is basically the shift in a delta to Y transformation.

If you pick a primary line-to-line phase at a delta primary as the reference, then relative to that reference look at a Y line-to-neutral voltage you will see a 30 degree shift or N*120 added to 30. And you can add a 180 shift by flipping the scope leads. Note: to run the experiment with a scope you should use some potential transformers or other isolating means. This potential transformer part of the comment is for those that want play with the phasing to an oscilloscope as has been shown in some previous posts and not burn up the probe ground leads.

The above error is why I need others to question my statements and calculations. The concept, brain, and keyboard are not always very well connected.

.

That's alright gar, I made a mistake once. Thought I was wrong!

 

[rbalex]

The trig identity is correct, but it seems to me that if we lose the "phi0",

then,

V1n = 170(sin(wt))

and,

V2n = 170(sin(wt +/- 180))



The phase shift is 180 degrees. That is they are 180 degrees out of phase.

Sorry, but there's no reason to loose the generality. You have simply identifed the special case where φ₀ = 0. So:

V1n = 170(sin(wt))
V2n = 170(sin(wt +/- 180)) = -170(sin(wt))

A ?180? phase displacement doesn't result in different phase,(i.e.,wt is still the same) unless you insist sign (or polarity) is necessary to define phase.

 

[LEO2854]

There are two ways to handle this.

For me I just accept 'because we do'

The other way takes 600 forum posts.


Good luck!

Looks like it will take even more than 600 posts...

 

[LEO2854]

This thread is hilarious. I love it!

If I place my dual-trace oscilloscope probe grounds on electrical ground and place one probe on one hot and the other probe on the other hot then the two waveforms that show on the oscilloscope are 180 degrees out of phase.

So in this sense there are two phases.

Why don't you all admit that the terminology is just convention and stop this silly discussion?

Good to see your having fun Welcome to the forum...:thumbsup::thumbsup:

 

[Besoeker]

If I place my dual-trace oscilloscope probe grounds on electrical ground and place one probe on one hot and the other probe on the other hot then the two waveforms that show on the oscilloscope are 180 degrees out of phase.

Been done. See post #404.

 

[T.M.Haja Sahib]

Been done. See post #404.

Request for some more doing with your scope.

Use X-Y mode in the scope to obtain Lissajous figure for 0 degree phase difference.Connect V1n to X leads and Vn2 to Y leads.What do you observe in the screen of your scope?