Why is residential wiring known as single phase?

[mivey]

Why I believe you do in the next few sentences...

Could you please site reference material that describes both to and from as indicating a single direction?

Thanks Jim, I was just about to point that out myself...
"Away" and "Toward" the neutral is not a valid choice.

Emphasis and underlining of "and" & "or" mine.

Honestly guys, if you would just put as much effort into understanding as you do into trying to misunderstand...

Who in the world has said they move in two different directions at the same time?
...
One option says the positive direction is defined as one linear direction across both windings (one way or the other), the other says the positive direction is directed from or to the neutral.

 

[mivey]

ooo, here we go again. As that little coulomb of charge passes the neutral it magically goes from moving in a positive to a negative motion. Nonsense.

Happens all the time in physics. It is called relativity. There is no positive and negative until we define the reference frame.

It's a given, not a choice.

Then a lot of physicists have wasted their lives studying relativity since they really should have been looking for the universal reference you think exists.

It's the physical reality of the circuit. At any given instance the voltage increases in one and only one direction across the length of the secondary coil. At any given instance the current moves in one and only one direction across the length of the secondary coil. At any given instance the power flows in one and only one direction across the length of the secondary coil.

"across the length of the secondary coil" is a choice you made, it is not a given.

Lol, they're moving IN-PHASE, IN-SYNC, and IN THE SAME DIRECTION as that little charge in the middle. They are NOT moving either "towards" or "away" from "it" unless you're going to claim your nose is moving away from you when you walk while your backside is moving towards you.

Visit the space station and have your body physically fit such that your weight is evenly dispersed throughout your body (to avoid an inertia sidetrack). Try three different exercises while there:

1) Handstand stomach crunch with your hands fastened to the floor and a bunjee cord on your feet.
2) Squat crunch with your feet fastened to the bulkhead and a bunjee cord on your hands.
3) Sitting crunch with your backside fastened to the floor and a bunjee cord on your feet and a bunjee cord on your hands.

We have the same motion for all three using three different reference frames. Now: Are your hands and backside moving towards your feet? Or are your feet and backside moving towards your hands? Or are your feet and hands both moving to your backside?

The reality is that all are true but we have to pick a reference frame. It is not a given.

 

[mivey]

How else does one interpret what you posted?
...

"Exclude other portions of the coil" sure sounds like you are saying the reference frame must be based on the physical. Specifically, it sure reads that you have said that in order for the reference to be valid, the physical portion of the coil containing the reference voltage must overlap the physical portion of the coil containing the voltage to be tested.

...

Pray tell: how else would you expect this to be interpreted?

Well pfalcon?

 

[T.M.Haja Sahib]

First, won't you answer the question I posed in post #814?

Sure.Applying two signals each across two sets of deflector plates X-Y subjects the electron dot on the scope screen to two harmonic oscillations,one along the X axis and other along the Y axis.Each oscillation can be represented as a sine function with respect to time.For example,for in phase two harmonic functions x=sinwt and y=sinwt applied to X-Y plates,the electron dot will trace a straight line on the scope screen,because eliminating t from the parametric equations x=sinwt and y=sinwt,one gets an equation of the type X'=Y',which is a straight line.Similarly for the out of phase two harmonic functions.

 

[pfalcon]

Thus a 180 deg phase shift in my real world does not equate to being "in phase".

Your "real world" is a specific application for which your mathematics and measurements will work perfectly fine. We've emphasized that numerous times. We aren't debating how the system can be used. Using "phase" in your stated context is a typical convention. Go with it.

 

[T.M.Haja Sahib]

120214-1728 EST

A mathematical model used to represent some physical process is of no value if it does not read on that process.

In my world I can not make any use of some model that says shifting a sine wave 180 deg produces a result that is "in phase" with the unshifted wave. That just does not work for my type of problem.

If I have a measurement signal A sin t and multiply this with a reference signal B sin t the result is A*B sin² t . Averaging this over N full cycles results in a DC signal +A*B/2. If the phase of the measurement signal changes by 180 deg, then the result is -A*B/2 . Clearly these two are not the same, and my meter reading will change from + to -. Very important for a readout from an LVDT. My definition of the term "in phase" would require the above two different input signals to produce the same output, but clearly I get a sign change.

Thus a 180 deg phase shift in my real world does not equate to being "in phase".

.

gar
Please clarify how the above relates to the topic of this thread.

 

[mivey]

gar
Please clarify how the above relates to the topic of this thread.

To what end? Have you not been following that there is a disagreement about the phase of a waveform and if two phases can be "resolved" down to one phase? This "resolving" fiasco is another attempt at trying to make the argument that the labels are also comprehensive system descriptions. The labels are just the names we have assigned, nothing more.

Bear in mind that when someone asks "why isn't a 120/240 system called two-phase" or "why is 120/240 called single-phase" the question is rooted in the difference between what something is called and what is physically present in the system. Multiple definitions for a single term also bring up questions. Also adding to the question is that the labels are not consistent between systems and they are certainly not completely descriptive of the physical systems.

The labels are simply names that we use by convention. There are valid physically-related reasons for using the labels, but the labels are not names that also provide a comprehensive description.

 

[pfalcon]

Mivey,
So let's take this one very small step at a time.

Arbitrarily in the order A, N, B and T=360 being one complete cycle.
T= 0; 0,0,0
T= 90; -120, 0, 120
T=180; 0,0,0
T=270; 120, 0, -120

Any problems here? Presuming VAC sinusoidal, arbitrary zero reference based on convenience and popularity, etc. etc.

 

[gar]

120215-0849 EST

rbalex:

Both gar and rattus were kind enough to respond as I have asked. There does appear to be some modest disagreement about what they believe ?in-synch? means. If I understand them correctly, rattus would say "in-synch" is synonymous with "in-phase"; I believe gar would say they aren?t necessarily. I'm open to being corrected by either or both of them.

Your conclusion is correct. I am using the broad definition of "in-sync", but in the context of its use with a generator I would agree with rattus's definition.

From dictionary.com

to cause to indicate the same time, as one timepiece with another: Synchronize your watches.
2. to cause to go on, move, operate, work, etc., at the same rate and exactly together: They synchronized their steps and walked on together.
3. Movies, Television .
a. to cause (sound and action) to match precisely: to synchronize the sound of footsteps with the actor's movements.
b. to match the sound and action in (a scene).
4. to cause to agree in time of occurrence; assign to the same time or period, as in a history.
5. to adjust the periodicities of (two or more electrical or mechanical devices) so that the periods are equal or integral multiples or fractions of each other.
verb (used without object)
6. to occur at the same time or coincide or agree in time.
7. to go on, move, operate, work, etc., at the same rate and exactly together; recur together.



Origin:
1615?25; < Greek synchron?zein to be contemporary with, equivalent to s?nchron ( os ) synchronous + -izein -ize

c.1624, "to occur at the same time," from Gk. synchronizein "be of the same time," from synchronos "happening at the same time" (see synchronous). The sense of "make synchronous" is first recorded 1806. Synchronized swimming is recorded from 1950.

Consider a conveyor line where all the pallets are mechanically linked together (positive transfer line) (a very dangerous type, high forces), then parts on two different pallets move "in-sync" when the transfer line moves. This means the slowest machine at any time determines the thruput at that time.

In contrast a floating pallet transfer system does not have parts moving "in-sync". If there is one dominate slow station on the line then both transfer system types have the same total thruput. But if various stations are slow and random in operation, then the floating pallet system with queues between stations may have a higher overall thruput.

.

 

[gar]

120215-0930 EST

T.M.

The original question included the word phase. So the discussion has drifted off to the subject of the word phase. And in turn this has followed many paths. My post #802 is intended to show that a 180 deg phase shift is not the same as an N*360 phase shift. This is important is signal detection and extraction of information from a signal.

I do in fact essentially use a multiplication means to extract the signal component (mechanical displacement) from an LVDT (Linear Variable Displacement Transducer) to obtain a DC output proportional to the mechanical displacement. As you move thru the electrical midpoint of the LVDT the output goes to near zero in amplitude and the output phase shifts by 180 degrees. This mid point is more muddy (not distinct) if a phase sensitive detector is not used.

Basically the product detector is a correlation detector.

.

 

[rbalex]

120215-0849 EST

rbalex:

Your conclusion is correct. I am using the broad definition of "in-sync", but in the context of its use with a generator I would agree with rattus's definition.
...

So far, we're basically in agreement with "in-sync" as it applies to generators. Do you agree with his definition of "in-phase"?

 

[T.M.Haja Sahib]

120215-0930 EST

T.M.

My post #802 is intended to show that a 180 deg phase shift is not the same as an N*360 phase shift.

.

gar
Agreed.But if a 180 degree phase shift is obtainable from a center tap 120/240v supply,it is not unique.The same 180 degree phase shift is obtainable from a pure 120V single phase supply.Why the 120/240v supply is also called single phase is that voltages across the domestic loads connected in that supply are in phase.Of course voltages with 180 degree phase shift for special purposes like yours can be derived as much from 120/240V supply as from pure 120V supply.Do you agree?

 

[T.M.Haja Sahib]

To what end? Have you not been following that there is a disagreement about the phase of a waveform and if two phases can be "resolved" down to one phase? This "resolving" fiasco is another attempt at trying to make the argument that the labels are also comprehensive system descriptions. The labels are just the names we have assigned, nothing more.

Bear in mind that when someone asks "why isn't a 120/240 system called two-phase" or "why is 120/240 called single-phase" the question is rooted in the difference between what something is called and what is physically present in the system. Multiple definitions for a single term also bring up questions. Also adding to the question is that the labels are not consistent between systems and they are certainly not completely descriptive of the physical systems.

The labels are simply names that we use by convention. There are valid physically-related reasons for using the labels, but the labels are not names that also provide a comprehensive description.

I am afraid you attempt to create a cult on 'phase'.
Please base your discussion on measurable quantities.
In the present case,please propose a method to measure 'phase' first.

 

[Besoeker]

Sure.Applying two signals each across two sets of deflector plates X-Y subjects the electron dot on the scope screen to two harmonic oscillations,one along the X axis and other along the Y axis.Each oscillation can be represented as a sine function with respect to time.For example,for in phase two harmonic functions x=sinwt and y=sinwt applied to X-Y plates,the electron dot will trace a straight line on the scope screen,because eliminating t from the parametric equations x=sinwt and y=sinwt,one gets an equation of the type X'=Y',which is a straight line.

Interesting, if somewhat cumbersome and convoluted.
Now who would describe the fundamental power frequency as a harmonic, I wonder.....
Anyway the post, regardless of provenance, concludes that the result is a straight line.
Do you know what slope it is and how you determine that?

 

[T.M.Haja Sahib]

Do you know what slope it is and how you determine that?

See the equation is Y=X.From the analytic geometry,the slope of line for this equation is
45 degree.

 

[Besoeker]

See the equation is Y=X.From the analytic geometry,the slope of line for this equation is
45 degree.

When I connected the probes as you requested in post #747, this is what I got:

 

[rattus]

When I connected the probes as you requested in post #747, this is what I got:

Which indicates the waves are 180 degrees out of phase which we already knew.

In my youth, we checked oscillator frequencies using Lissajous patterns.

 

[jim dungar]

Emphasis and underlining of "and" & "or" mine.

Honestly guys, if you would just put as much effort into understanding as you do into trying to misunderstand...

You describe two separate conditions

One option says the positive direction is defined as one linear direction across both windings (one way or the other),...

clearly one direction correct?

...the other says the positive direction is directed from or to the neutral.

From isn't this direction #1? To isn't this direction #2? do you see how there could be some confusion?

Based on your accusation, that I am trying to mislead, I will try again.
As I read option #1, in the bottom halve of the winding the current is flowing either from or to the center, and in the top halve it is then flowing either to or from isn't it? Gee this sounds like your second option.

So for option #2, do you mean the current in the both halves can be flowing from the neutral or both can be flowing to the neutral? I know, in this discussion, loop currents have been drawn showing this method.

What did you mean to say?

 

[Besoeker]

In my youth, we checked oscillator frequencies using Lissajous patterns.

A known reference frequency to determine another?
As students, we played around with them and had the principles explained.
But not something I've had a need to use in real life.

 

[rattus]

A known reference frequency to determine another?
As students, we played around with them and had the principles explained.
But not something I've had a need to use in real life.

We used an hp audio oscillator as the reference and a Heathkit scope to check the frequencies of audiometers. This was in the late 50s. Vacuum tube days, or should I say valves?