Why is residential wiring known as single phase?

[Besoeker]

Hmm.. I requested you to state the differences between AC and DC voltages.

Let's cut to the chase. You know perfectly well that I understand the differences between AC and DC.
Thus, one would guess that you're trying to make a point.
So, stop beating about the bush and just spit it out.

 

[jim dungar]

I don't see your point. I have not made such a claim. The waveforms are bi-directional and current changes direction every 1/2 cycle. I believe it is the default assignment of a positive direction that is making you think there is an inconsistency.

You are the one who assigned current directions to your drawing. Are you saying they serve no purpose? I thought you put them there to analyze your point about being able to connect separate sources to a common load.

And for the unknownth time - I have not said which direction is positive or negative, nor said any direction is mandatory.
I have said the physical construction of the transformer windings creates an absolute. If you want a different absolute - change the physical. If the output of the windings are 'in-phase' when connected in parallel, they remain 'in-phase' when connected in series, given the terminal relationships are maintained.

 

[Rick Christopherson]

And you will note that the math and the real world both agree.

I do not disagree with the problem you have presented, but it is not applicable to the comments I have been making. I have too much going on this weekend to try to mess around with trying to keep you on-topic. Instead of trying to head off on misleading tangents, I would appreciate it if you could stay on the topic we were discussing.

 

[rbalex]

120218-2038 EST

I am in stitches as I read this discussion. I just can't stop laughing.

It has also become quite unclear who said what and when, and there are probably at least three different threads intertwined.

For this group of all English speaking persons there is a real language translation problem between them. I don't know how many different definitions are being used but there are many. Agreement is certainly not possible with non-compatible definitions.

.

As far as I know there have been three properly submitted formal definitions proposed:

[1] Weisstein, Eric W. "Phase." From MathWorld--A Wolfram Web Resource. http://mathworld.wolfram.com/Phase.html:
​

Phase: The angular position of a quantity.
For example, the phase of a function f(wt+Φ₀) as a function of time is: Φ(t)= wt+Φ₀
(Post 132)​

[2] Phase: Phase is the fractional part of a period through which time or the associated time angle wt has advanced from an arbitrary reference.......
​

[Kerchner and Corcoran, Alternating-Current Circuits, Wiley, 1951]
(Post 844)

​

[3] From IEEE Std 100 The IEEE Standard Dictionary of Electrical and Electronic Terms:
​

phase (of a periodic phenomenon ?(t), for a particular value of t) The fractional part t/P of the period P through which ? has advanced relative to an arbitrary origin.
Note: The origin is usually taken at the last previous passage through zero from the negative to the positive direction. See also: control system, feedback; simple sine-wave quantity. (IM) [120]
(Post 921)
​

I offered the first and third; rattus offered the second.

Within the context of, "Why is residential wiring known as single phase?", they are compatible with each other and confirm the concept that magnitude (amplitude) and sign (polarity) are not essential with respect to phase of a periodic function, only the period and initial value are relevant. Of course, magnitude and sign aren't required to be different, but they can be.

There have been tons of descriptions about what they look like or how to measure them; but, I don't believe there have been any other properly cited alternate definition.​

 

[mivey]

You are the one who assigned current directions to your drawing. Are you saying they serve no purpose? I thought you put them there to analyze your point about being able to connect separate sources to a common load.

You are claiming an inconsistency where there is none.

And for the unknownth time - I have not said which direction is positive or negative, nor said any direction is mandatory.

A lot of double-talk. You claim either direction is fine but then claim there are only in-phase voltages present at the secondary. I demonstrate how both are present and you say you don't mandate a direction, but then say that only the in-phase is the real world which does mandate a direction.

I have said the physical construction of the transformer windings creates an absolute.

See? Either direction is fine but really only one direction creates an absolute. Double-talk.

If you want a different absolute - change the physical. If the output of the windings are 'in-phase' when connected in parallel, they remain 'in-phase' when connected in series, given the terminal relationships are maintained.

I have shown that your "absolute" is only half of the story. I have clearly demonstrated that a set of voltages also exist at the secondary which are not in phase. I guess you agree but don't agree?

 

[mivey]

I do not disagree with the problem you have presented, but it is not applicable to the comments I have been making.

It is in direct response to your comments here:

...We're talking about a single phase transformer...I am saying this situation does not have a real phase shift. It comes from an inversion that can appear mathematically as a phase shift if one chooses.

You said an inversion in a single-phase transformer is not a phase shift. I showed you a direct example of where an inversion was used in a single phase transformer (actually two of them) showing it is a phase shift.

I have too much going on this weekend to try to mess around with trying to keep you on-topic. Instead of trying to head off on misleading tangents, I would appreciate it if you could stay on the topic we were discussing.

The post was directly addressing your claim that an inversion in a single-phase transformer is not a phase shift. I provide a real-world example that proves your statement is incorrect. Instead of facing it, you want to claim it is off-topic. Not quite what I was expecting from you.

 

[Rick Christopherson]

The post was directly addressing your claim that an inversion in a single-phase transformer is not a phase shift. I provide a real-world example that proves your statement is incorrect. Instead of facing it, you want to claim it is off-topic. Not quite what I was expecting from you.

Please be more careful as you read. Your interpretation will not be found in any words I have chosen.

I said the inversion is real and the phase shift is apparent. Your example did not address this statement in any manner.

 

[mivey]

Please be more careful as you read. Your interpretation will not be found in any words I have chosen.

I said the inversion is real and the phase shift is apparent. Your example did not address this statement in any manner.

The inverted voltages become the missing third phase. The entire standard electric world recognizes these to be a different phase. Why don't you?

 

[Rick Christopherson]

The inverted voltages become the missing third phase. The entire standard electric world recognizes these to be a different phase. Why don't you?

Why don't you come back to this discussion after you've had some sleep or looked at it a little closer. You're not on the same page.

 

[mivey]

There have been tons of descriptions about what they look like or how to measure them; but, I don't believe there have been any other properly cited alternate definition.

Dismissing the facts because the answers are not in a format you like is not a strong argument. Our industry presents a different view than what you present. You are not going to find support for the idea that a 180? displacement is "in phase". I'm not sure what definition you are looking for, but keep in mind that the people writing the textbooks and teaching the classes are not just pulling the idea of a 180? displacement being out-of-phase out of thin air. They have a basis for that consistent presentation and the entire industry seems to use the same basis.

Our industry does not support the idea that a 180? displacement is somehow considered "in phase".

Here are some more examples to add to the ones I gave you before (I added highlights):

phase
1. Any of the forms, recurring in cycles, in which the Moon or a planet appears in the sky.
2. One of a set of possible homogenous, discrete states of a physical system. States of matter such as solid and liquid are examples of phases, as are different crystal lattice structures in metals such as iron. See also phase transitionstate of matter
3. A measure of how far some cyclic behavior, such as wave motion, has proceeded through its cycle, measured in degrees or radians. At the beginning of the phase, its value is zero; at one quarter of its cycle, its phase is 90 degrees (/2 radians); halfway through the cycle its value is 180 degrees ( radians), and so on. The phase angle between two waves is a measure of their difference in phase. Two waves of the same frequency that are perfectly in phase have phase angle zero; if one wave is ahead of the other by a quarter cycle, its phase angle 90 degrees (/2 radians); waves that are perfectly out of phase have phase angle 180 degrees ( radians), and so on. See more at wave.

The American Heritage? Science Dictionary Copyright ? 2005 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

phase
In physics, the term phase has two distinct meanings. The first is a property of waves. If we think of a wave as having peaks and valleys with a zero-crossing between them, the phase of the wave is defined as the distance between the first zero-crossing and the point in space defined as the origin. Two waves with the same frequency are "in phase" if they have the same phase and therefore line up everywhere. Waves with the same frequency but different phases are "out of phase." The term phase also refers to states of matter. For example, water can exist in liquid, solid, and gas phases. In each phase, the water molecules interact differently, and the aggregate of many molecules has distinct physical properties. Condensed matter systems can have interesting and exotic phases, such as superfluid, superconducting, and quantum critical phases. Quantum fields such as the Higgs field can also exist in different phases.

phase (physics)
In physics, a stage in an oscillatory motion, such as a wave motion: two waves are in phase when their peaks and their troughs coincide. Otherwise, there is a phase difference, which has consequences in interference phenomena and alternating current electricity.

When comparing the phases of two or more periodic motions, such as waves, the motions are said to be in phase when corresponding points reach maximum or minimum displacements simultaneously. If the crests of two waves pass the same point or line at the same time, then they are in phase for that position; however, if the crest of one and the trough of the other pass at the same time, the phase angles differ by 180?, or π radians, and the waves are said to be out of phase (by 180? in this case).

Two points are said to be in-phase if they behave exactly the same; that is, if they are a multiple of a wavelength apart. If two points are not in-phase, then they are out-of-phase . Since a wavelength corresponds to one complete vibration, or one complete revolution, one wavelength is often expressed as 360?. So in-phase points are separated by n360?. Out-of-phase points can be any number of degrees apart. Although we usually speak of points which are separated by 90?, 180?, or 270?.

Page 6 of http://www.physics.isu.edu/~hackmart/waves100.PDF

Phase (waves)
...
It is apparent that the positions of the peaks (X), troughs (Y) and zero-crossing points (Z) of both waves all coincide. The phase difference of the waves is thus zero, or, the waves are said to be in phase.

If the two in-phase waves A and B are added together (for instance, if they are two light waves shining on the same spot), the result will be a third wave of the same wavelength as A and B, but with twice the amplitude. This is known as constructive interference.

...

However, it can be seen that although the zero-crossing points (Z) are coincident between A and C, the positions of the peaks and troughs are reversed, that is an X on A becomes a Y on C, and vice versa. In this case, the two waves are said to be out of phase or in antiphase, or the phase difference of the two waves is π radians, or half the wavelength (λ/2).

If waves A and C are added, the result is a wave of zero amplitude. This is called destructive interference.

Phase
When a wave passes through a medium, the particles of the medium vibrate about their respective mean positions in the same manner, but reach the corresponding positions in their paths at different instants of time. These relative positions represent the phase of the motion. It is measured either in terms of the angle that the particle has described (denoted as a fraction of 2p) or the time that has elapsed (measured as a fraction of the time period T), since the particle last passed through its mean position in the positive direction.
The phase difference between any two particles indicates the extent by which they are out of step with each other.
For example, a particle on the crest and a particle on the adjacent trough of a wave differ in phase by 180? or pi radians.

In Figure 4-5a the two waves are exactly in phase, with their maximum and minimum points matching perfectly. Applying the principle of superposition to the two waves, the resultant wave is seen to have the same amplitude and frequency but twice the amplitude 2A of either initial wave. This is an example of constructive interference. In Figure 4-5b the two curves are exactly out of phase, with the crest of one falling on the trough of the other, and so on. Since one wave effectively cancels the effect of the other at each point, the resultant wave has zero displacement everywhere, as indicated by the solid black line. This is an example of destructive interference.

Wave Interaction or Interference

...When they are in phase (so that the peaks and valleys of one are exactly aligned with those of the other), they combine to double the displacement of either wave acting alone. When they are completely out of phase (so that the peaks of one wave are exactly aligned with the valleys of the other wave), they combine to cancel each other out.

See page 14 of http://physics.ucdavis.edu/physics7/Physics7/7C_common/TrigReview.pdf

 

[mivey]

Why don't you come back to this discussion after you've had some sleep or looked at it a little closer. You're not on the same page.

OK. Perhaps you could clarify.

 

[jim dungar]

See? Either direction is fine but really only one direction creates an absolute. Double-talk.

Chose a direction and use it consistently is not double-talk.
If you claim that the two winding outputs are 'in phase' when they are connected in parallel then you have chosen a direction for each output, in the industry standard transformer connections I have been focussing on, the output of winding X1-X2 is in phase with the output of winding X3-X4. This is a simple fact.

I have shown that your "absolute" is only half of the story. I have clearly demonstrated that a set of voltages also exist at the secondary which are not in phase.

All you have done is show how you can move your arbitrary reference point to produce two circuits that are out of phase, but you consistently ignore what really exists.

How does your math tell these two connections apart?
Afterall Van=-Vna and Vnb=-Vbn

Can either of these be used to feed Besoeker's rectifiers?
Do the waveforms look the same?

 

[rbalex]

Dismissing the facts because the answers are not in a format you like is not a strong argument. ...

YES - I wish really you would stop doing that - it's very annoying.

... Our industry presents a different view than what you present. You are not going to find support for the idea that a 180? displacement is "in phase". I'm not sure what definition you are looking for, but keep in mind that the people writing the textbooks and teaching the classes are not just pulling the idea of a 180? displacement being out-of-phase out of thin air. They have a basis for that consistent presentation and the entire industry seems to use the same basis.

Our industry does not support the idea that a 180? displacement is somehow considered "in phase".

Here are some more examples to add to the ones I gave you before (I added highlights):

I’m aware the authors didn’t pull their “180? displacement” concepts out of the air. I’m also aware the original use of the term “single-phase” as it applies to electrical phenomena predates anything even remotely like oscilloscopes by at least five years.

However, I do sincerely appreciate your efforts to offer proper definitions - you have done as I asked, thank you.

Although I'm sure you would like to, since ambiguity and "bait & switch" are some of your favorite tactics, we can't use all of the various definitions interchangeably. Pick one and only one of the definitions you propose to apply to the topic "Why is residential wiring known as single phase?” If we both agree to it, then a proper stipulation has been developed between us; i.e., no one else is obligated to accept it. Otherwise it’s just arguing to argue and we can both go home - each confident that we "won" the argument.

I'm sorry but you don't get to assert yours or any branch of the industry’s colloquialisms is mandatory for everyone - yet (That’s an improper “stipulation.”) But possibly in the future.

I would remind you that examples themselves are not definitions; at best, they are descriptions.

Edit Add: My boss actually expects production from me occasionally, so I may not be able to respond quickly. It's one of the reasons I usually limit myself to hazardous locations; it doesn't take too much of my time.

 

[rattus]

Quote Originally Posted by rattus View Post
Alright, then let phi0 be zero. Now the phases of the V1 and V2 are:

phi1 = (wt)

phi2 = (wt +/- 180)

They are clearly not equal. The angular positions of the two waves are not the same. We have a phase displacement or phase shift. They are out of phase. You have shown V2 is the negative of V1 but that does not prove your point.

Maybe there is something I missed. Tell me if I am wrong.

Those equations definitely aren't equal; but when used as the arguments for reduced periodic functions, such as Sine or Cosine, the phases [wt] remain the same.

How do you justify dropping the 180 from phi2 which is a phase angle according to the definitions? And, don't refer us to some past post or ask us if we believe in trig. Tell us again how you do that.

If V1 and V2 were in phase, we could short L1 to L2 and nothing would happen.

 

[Besoeker]

0

Can either of these be used to feed Besoeker's rectifiers?
Do the waveforms look the same?

View attachment 6487

For the rectifier arrangements I've given here (posts #432 and #1004), the output voltages would be different for both waveform and magnitude with your two different arrangements.

 

[jim dungar]

For the rectifier arrangements I've given here (posts #432 and #1004), the output voltages would be different for both waveform and magnitude with your two different arrangements.

Two different physical arrangements, two different waveforms.
Both have Van and Vbn as well as Van and Vnb. Why aren't both arrangements usable?

Can you modify your rectifier circuits to work the 'alternate' physical arrangement?

 

[pfalcon]

Such silliness.

The center tap is obfuscation for Mivey and Besoeker.

Bottom line with only the two ends of the secondary coil A & B. They can dual trace +240V<0 in one direction and -240<180 in the other direction. Therefore AB is 180 degrees out of phase with BA.

After all, if Mivey can excuse referencing one direction when measuring AN and reversing direction then I can reverse my reference frame to measure BA to get the above.

 

[Besoeker]

Two different physical arrangements, two different waveforms.
Both have Van and Vbn as well as Van and Vnb. Why aren't both arrangements usable?

Can you modify your rectifier circuits to work the 'alternate' physical arrangement?

Of course you can connect the windings is series or parallel. The usual residential arrangement is in series.
You get tw0 120V supplies in anti-phase.
Without that that anti-phase, the circuit I presented in post #1004 couldn't work.
But it does.

 

[rbalex]

Quote Originally Posted by rattus View Post
Alright, then let phi0 be zero. Now the phases of the V1 and V2 are:

phi1 = (wt)

phi2 = (wt +/- 180)

They are clearly not equal. The angular positions of the two waves are not the same. We have a phase displacement or phase shift. They are out of phase. You have shown V2 is the negative of V1 but that does not prove your point.

Maybe there is something I missed. Tell me if I am wrong.



How do you justify dropping the 180 from phi2 which is a phase angle according to the definitions? And, don't refer us to some past post or ask us if we believe in trig. Tell us again how you do that.

If V1 and V2 were in phase, we could short L1 to L2 and nothing would happen.

If you accepted what identity means mathematically, your question was answered in the quotation.

Originally Posted by rbalex
Those equations definitely aren't equal; but when used as the arguments for reduced periodic functions, such as Sine or Cosine, the phases [wt] remain the same.

Nevertheless, I refer you Post 696 where I underlined all the complicated math terms and bracketed the phases of the trig identity. If you can make the emotional/intellectual leap to accept (? 180?) is a specific case of φ₀ rather than a general case of φ, and apply this to periodic Sine functions, then the phase of both equations is equal, in fact identically equal, and the sign is irrelevant.

 

[ronaldrc]

Let me see now, what have I learned ?

1.--Different polarity and Phase are the same thing, because one terminal is positive and one is Negative.
That makes them 180 degrees offset from each other. So now I know any Electrical circuit is two phase.

2.--Pulse, Pulse and Phase are the same thing.

In Beos Rectifier circuit which is fed by a three phase source which have 3 secondary center tap windings
which produces a negative and a positive too control the two rails, is really 6 phases not pulses.

Its not one negative polarity to control one rail and a positive polarity to control the other rail like I thought.

I'm getting so smart I can't stand myself, let alone you all being able to stand me. :slaphead: :rotflmao: