Why is residential wiring known as single phase?

[rbalex]

Let me just get this right.
Are saying that the current and voltage are in phase with a 0.8pf load?

First, thanks for asking in the interrogatory. (Sincerely)

Second, I’m saying they have the same phase. They must for any linear circuit; i.e., they must have the same period P and the fraction t/P from t=t₀ throughout their common period must be identical .

Phase is a defined term. See rattus' latest post. “In phase” is an undefined colloquialism. We all kind of understand it, but it is informal and ambiguous nonetheless. It may be synonymous with “in sync” but not necessarily; previously, you have said they aren't but haven't offered a significant distinction.

 

[rbalex]

Bob is saying that V1 is in phase with itself (I believe that) and that V1 is in phase with its inverse. How can that be?

Again rattushopper, you misread, you misread. I have said they have the same phase. You must read your own definition most carefully.

Edit add: You must make no more false assertions or you will be ignored. You may say something like, "I think Bob means..." but you must never again say "Bob is saying..." or anything similar - I will speak for myself.

 

[rattus]

More Phasors:

More Phasors:

My phasor diagram comprises fixed phasors, you know those we use in AC analyses with impedances.

The diagram clearly shows V2 displaced by 180 degrees from V1.

Furthermore, Fig. 6 in post 1493 shows clearly, the phase shift, lead or lag, to be measured between positive peaks. Could be measured between other LIKE points as well.

 

[rbalex]

My phasor diagram comprises fixed phasors, you know those we use in AC analyses with impedances.

The diagram clearly shows V2 displaced by 180 degrees from V1.

Yes-so?

Furthermore, Fig. 6 in post 1493 shows clearly, the phase shift, lead or lag, to be measured between positive peaks. Could be measured between other LIKE points as well.

Indeed it does- and how does that change the meaning of "Phase is the fractional part of a period through which time or the associated time angle wt has advanced from an arbitrary reference."?

 

[rattus]

Again rattushopper, you misread, you misread. I have said they have the same phase. You must read your own definition most carefully.

Edit add: You must make no more false assertions or you will be ignored. You may say something like, "I think Bob means..." but you must never again say "Bob is saying..." or anything similar - I will speak for myself.

Are you saying that (wt) = (wt + 180)?

 

[rattus]

Yes-so?

Indeed it does- and how does that change the meaning of "Phase is the fractional part of a period through which time or the associated time angle wt has advanced from an arbitrary reference."?

It doesn't. It shows the phase difference, which is 180 degrees.

 

[rbalex]

Are you saying that (wt) = (wt + 180)?

Thank you too for asking in the interrogatory.

I am saying that for a 120/240V residential system:

?120V ? sin([ωt+φ]),
?120V ? sin([ωt+φ]?180?),
?240V ? sin([ωt+φ]) and
?240V ? sin([ωt+φ]?180?)

all have the same phase no matter how you legitimately determine the voltage functions.

That is, where they have a common t₀ they all have the same period P and t/P will be identical for every value of t throughout the period.

 

[rattus]

Thank you too for asking in the interrogatory.

I am saying that for a 120/240V residential system:

?120V ? sin([ωt+φ]),
?120V ? sin([ωt+φ]?180?),
?240V ? sin([ωt+φ]) and
?240V ? sin([ωt+φ]?180?)

all have the same phase no matter how you legitimately determine the voltage functions.

That is, where they have a common t₀ they all have the same period P and t/P will be identical for every value of t throughout the period.

The phase is (wt +phi0) in some cases and (wt +phi0 +180) in others.''

Or another way to look at it is the phase angles are phi0 in some cases and phi0 +180 in others. Can't be in phase with different phase angles.

You can't just dump the 180. It must be added to phi0. If you do there is no phase difference. You can't trig it away either.

 

[rbalex]

The phase is (wt +phi0) in some cases and (wt +phi0 +180) in others.

You can't just dump the 180. It must be added to phi0. If you do there is no phase difference. You can't trig it away either.

Are you saying that ?180? will alter the period or t/P over the period for a 120/240V residential system?

 

[gar]

120227-1957 EST

I believe the problem is I am talking about the "phase difference" between two waveforms. Thus, I am not talking about a phase. In-phase is a phase difference of 0 degrees. A 180 degree phase difference is an inversion or a delay of one half cycle or any equivalent description.

Also my definition of sync is not of necessity that two items are overlays of one another. Just that they work together.

.

 

[rbalex]

120227-1957 EST

I believe the problem is I am talking about the "phase difference" between two waveforms. Thus, I am not talking about a phase. In-phase is a phase difference of 0 degrees. A 180 degree phase difference is an inversion or a delay of one half cycle or any equivalent description.

Also my definition of sync is not of necessity that two items are overlays of one another. Just that they work together.

.

Thanks for the clarification.

While we're at it, can you "...differentiate A sin ([ωt+φ]) from ?A sin ([ωt+φ]?180?) for determining period P and the fraction t/P over the period of a single-phase system;" specifically a 120/240V residential system if it were in a "black-box"? (I'm honestly clueless)

 

[rattus]

Are you saying that ?180? will alter the period or t/P over the period for a 120/240V residential system?

Now how can I alter the period of poco generated sinusoid? Of course it doesn't alter the period.

I am saying that you cannot ignore the 180 degrees. phi0 is part of the phase expression, then any constant added to it is also part of the expression as well.

*"When i and e are in phase. If the current i reaches its maximum positive value at the same instant at which the emf e reaches its maximum positive value, the current is said to be in phase with the emf."
*[Tang, Alternating Current Circuits, International, 1960].

Clearly a sinusoid and its inverse cannot reach this state, ever. Therefore the waves are out of phase.

 

[rbalex]

Now how can I alter the period of poco generated sinusoid? Of course it doesn't alter the period.

I am saying that you cannot ignore the 180 degrees. phi0 is part of the phase expression, then any constant added to it is also part of the expression as well.

*"When i and e are in phase. If the current i reaches its maximum positive value at the same instant at which the emf e reaches its maximum positive value, the current is said to be in phase with the emf."
*[Tang, Alternating Current Circuits, International, 1960].

Clearly a sinusoid and its inverse cannot reach this state, ever. Therefore the waves are out of phase.

Now you are attempting to change the definition; with a description, no less. Push it much further and you will be ignored.

Besides, the phase relevant to the OP is for voltages, not voltages and currents. So one more try: does the ?180? alter the period or t/P over the period for the voltages of a 120/240V residential system?

 

[gar]

120227-2126 EST

rbalex:

I do not understand your question.

I believe I have a black box with 3 terminals to consider. These terminals are labeled A, N, and B. Since a conventional single phase system ("specifically a 120/240V residential system ") was referenced, then
v_AN = - v_BN for the instantaneous voltages. I also assume these are perfect sine waves.

To determine the period I need some external time measuring device, or the frequency of the sine wave has to defined as part of the problem. Maybe "specifically a 120/240V residential system" means the period is exactly 1/60 second.

Between what terminals is "A sin ([ωt+φ])" and between what terminals is "?A sin ([ωt+φ]?180?)"? What kind of differentiation do you want?

A sin ([ωt+φ]) is not equal to A sin ([ωt+φ]?180?),
A sin ([ωt+φ]) is equal to - A sin ([ωt+φ]?180?).

d ( sin ([ωt+φ]) ) / dt = ω * cos ( ([ωt+φ]) ), but that is just the slope of the sin curve.

.

 

[rattus]

Now you are attempting to change the definition; with a description, no less. Push it much further and you will be ignored.

Besides, the phase relevant to the OP is for voltages, not voltages and currents. So one more try: does the ?180? alter the period or t/P over the period for the voltages of a 120/240V residential system?

What arrogance! That is one way to avoid the issue.

That 'description' was good enough for thousands of EE students over the years. Whatever you call it, those are the conditions for in phase.

The 'description' applies just as well to voltage waveforms as you well know. It is pointless to claim otherwise.

I have already answered your question about the period which was irrelevant anyway. Just another dodge.

 

[rbalex]

120227-2126 EST

rbalex:

I do not understand your question.

I believe I have a black box with 3 terminals to consider. These terminals are labeled A, N, and B. Since a conventional single phase system ("specifically a 120/240V residential system ") was referenced, then
v_AN = - v_BN for the instantaneous voltages. I also assume these are perfect sine waves.

To determine the period I need some external time measuring device, or the frequency of the sine wave has to defined as part of the problem. Maybe "specifically a 120/240V residential system" means the period is exactly 1/60 second.

Between what terminals is "A sin ([ωt+φ])" and between what terminals is "?A sin ([ωt+φ]?180?)"? What kind of differentiation do you want?

A sin ([ωt+φ]) is not equal to A sin ([ωt+φ]?180?),
A sin ([ωt+φ]) is equal to - A sin ([ωt+φ]?180?).

d ( sin ([ωt+φ]) ) / dt = ω * cos ( ([ωt+φ]) ), but that is just the slope of the sin curve.

.

I'm not quite sure how to frame this.

Assuming you have a conventional residential 120/240V setup, A-N-B. For any two randomly selected sets of terminals, would any conventional measurement technique result in seeing a different period P or imply a different fraction t/P of the two periods at any time t between the measured voltage functions.

 

[rbalex]

What arrogance! That is one way to avoid the issue.

That 'description' was good enough for thousands of EE students over the years. Whatever you call it, those are the conditions for in phase.

The 'description' applies just as well to voltage waveforms as you well know. It is pointless to claim otherwise.

I have already answered your question about the period which was irrelevant anyway. Just another dodge.

Do you differentiate "in phase" from phase or do you want to replace your earlier definition?

 

[rbalex]

What arrogance! That is one way to avoid the issue.

That 'description' was good enough for thousands of EE students over the years. Whatever you call it, those are the conditions for in phase.

The 'description' applies just as well to voltage waveforms as you well know. It is pointless to claim otherwise.

I have already answered your question about the period which was irrelevant anyway. Just another dodge.

I went back to 1513; I did the very thing that I hate. I accused you of something, rather than ask if that was what you were intending. I humbly and sincerely apologize.

 

[rattus]

I went back to 1513; I did the very thing that I hate. I accused you of something, rather than ask if that was what you were intending. I humbly and sincerely apologize.

Perhaps you can provide an official definition of "in phase". Meanwhile, I believe the statement from Tang's textbook will suffice.

I repeat, positive peaks can never coincide in a sinusoidal wave and its inverse, therefore, the two waves can never be in phase.

Let us look at it another way:

Let the expressions for the phases of the two waves be:

phi1 = (wt + phi0) for V1
phi2 = (wt + theta0) for V2

The waves are in phase if and only if phi0 = theta0

New let phi0 be zero and let theta0 = PI.

0 NE PI

Therefore

phi1 NE phi2

Are those waves in phase??

Now don't answer with another question. Just tell us how they can be in phase with phi0 NE theta0.

 

[pfalcon]

They cross zero at the same time but going in opposite directions. That makes them NOT in phase.

LoL. They go in the same direction. It's your leads that go in opposite directions. As always. You keep forgetting to invert the magnitude when you invert the leads.