Why is residential wiring known as single phase?

[T.M.Haja Sahib]

They do not "act simutaneously" in Besoeker's circuit but are operating like two voltages with a 180? displacement. In fact, Besoeker designed it to operate that way and his circuit requires two phase-opposed voltages. It really is just that simple.

Then what B's circuit has to do with the residential single phase supply system under discussion ?

 

[Besoeker]

You are too reluctant even to say a yes or no to continue the discussion along this line.......

Not at all reluctant.
Would just like you to think a little more about a 120-0-120 system.
What do you think the 120V means?
And how would you define your instantaneous voltage vector voltages?

 

[Besoeker]

They do not "act simutaneously" in Besoeker's circuit but are operating like two voltages with a 180? displacement. In fact, Besoeker designed it to operate that way and his circuit requires two phase-opposed voltages.

Got it in one.:thumbsup:

It really is just that simple.

If only.....

 

[mivey]

Then what B's circuit has to do with the residential single phase supply system under discussion ?

Circuits of this type will work just fine on a residential service. The residential transformer can deliver two smaller voltages with a 0? displacement or two smaller voltages with a 180? displacement. Both are real voltage sets. Contrary to what some here think, circuits like Besoeker's prove that the 180? voltage set is a real set and not just a measurement "ghost".

 

[T.M.Haja Sahib]

Not at all reluctant.
Would just like you to think a little more about a 120-0-120 system.
What do you think the 120V means?
And how would you define your instantaneous voltage vector voltages?

This is deal.
I will define instantaneous values for the system under discussion as 120-0-(-120) system.This point I made to you already.

 

[Besoeker]

Then what B's circuit has to do with the residential single phase supply system under discussion ?

It's the same. Except for the voltage.
Actually, in my initial design I started with 100-0-100. The voltage was at that level to keep a good signal to noise ratio. But the dissipation in the filters was a bit high.
My colleagues in our lighting division work with much lower voltages for the synchronising signals and are having a bit of a problem in some installations.
I have a notion I might get dragged into that some more.
That's life, I guess.

 

[T.M.Haja Sahib]

Circuits of this type will work just fine on a residential service. The residential transformer can deliver two smaller voltages with a 0? displacement or two smaller voltages with a 180? displacement. Both are real voltage sets. Contrary to what some here think, circuits like Besoeker's prove that the 180? voltage set is a real set and not just a measurement "ghost".

I already requested B to explain the working principle of his device.He never did.You seem to support him blindly......

 

[mivey]

I already requested B to explain the working principle of his device.He never did.

Any competent engineer should be able to look at Besoeker's circuit and figure it out. It should not require him to explain. It is a common fundamental concept, but just used to make a not-so-common product.

If it helps you any, just go back to your circuit textbooks and look up any two-diode full wave rectifier circuit. That should make it clear if you understand circuits. If you still don't understand, please ask and I'll be glad to help.

You seem to support him blindly......

Not at all. I rarely do anything blindly. In fact, I usually study things in what might be considered extreme detail to many. I'm smarter than the average bear and quite capable of standing on my own two feet and deciding for myself what is correct and incorrect. If it appears there is a lack of supporting information, it might help you to know that I have read hundreds and hundreds of posts on these topics as well as many of Besoeker's previous posts in other threads.

 

[Besoeker]

This is deal.
I will define instantaneous values for the system under discussion as 120-0-(-120) system.This point I made to you already.

Then it is an erroneous definition.
The instantaneous value is not a single number except at a single instant in time. Over time, it varies with respect to time as V_msin(ωt) in one winding and as V_msin(ωt+π) in the other when measured with respect to neutral.
The instantaneous value will be +120V twice during the positive half cycle at π/4 and 3π/4 and -120V at 5π/4 and 7π/4.

Now, how about you explain what you mean by instantaneous vector voltages?

 

[jim dungar]

It is odd how some take issue with moving one lead to measure a 180? voltage set, but have no problems moving two leads to measure the 0? voltage set. And for the players on the other team: both voltage sets are valid, real, and available voltage sets.

It is surprising how you have missed the primary point of the past hundreds of postings: 'you can choose to use the neutral' versus 'you must use the neutral'.

Vnb and -vnb are not two separate actual voltages, they are a single voltage with different reference points.
A single wiring diagram posted by Besoeker has been used to demonstrate both a shift and the lack of a shift with absolutely no wiring change. So which view is real?

I know you prefer to treat the sources as 'black boxes', but that is not always possible. There is a huge difference between wiring two transformer windings in an additive series connection, versus an open wye, or an open delta. Why not base our math on the wiring of the source instead of the wiring of the load?

 

[zbang]

Physics aside, this whole discussion really reminds me of the old joke:

"Why do you call that a banjo?"
"Because it sounds like one."

Almost all electricians and engineers will call a 120/240v (2 ends + center connection from a center-tapped transformer) service "single phase" although a few will call it "split phase". Don't think I've ever heard it called "two phase" except by homeowners . Once you explain what is historically known as "two phase", they get it.

Well on the way to 600 posts...

 

[pfalcon]

No one is saying there are two phases. We are discussing phase angles, namely he phase angles of V1n and V2n.

Different phase angles would define that they're different phases. So yes, you really are saying there are two phases by declaring they have different phase angles.

V1n and V2n are defined relative to N. Since they are defined relative to N, we must measure them relative to N. Then there appears to be 180 degrees separation, therefore there is. If we define the voltages differently as Jim Dungar is wont to do, then there is 0 degrees separation. V1n and V2n are separate entities; there is no reason to

V1n and V2n are not defined relative to N. You don't have to measure them relative to N. Magicians make elephants appear to vanish, therefore it is. Wait. No. Appearance means nothing. Phase is phase. It is what it is. Not what you want it to be. Not what view you take of it. It is what it is.

It doesn't matter that these voltages are obtained from a center tapped winding. They could be from separate transformers or generators. Don't be hung up on this common source notion. V1n and V2n are separate entities and should be treated as such.

It actually does matter where they came from. I guarantee if you tried to set this up from separate transformer windings and tie them common you would get in trouble when you started to apply unbalanced loads. And V1n/V2n are not separate entities on heater elements. Therefore they can't be treated as such.

 

[pfalcon]

Not true at all. The voltages can be used either way. Both are valid and depend on the circuit.

We've already agreed on this mivey in the prior thread. Usage and "Technically Correct" are different animals.

I'm more focused on how the voltages are used, not how they are derived as they can be derived in a miriad of ways. What becomes important is that the waveforms are what they are. All the talk about the "windings in phase" with each other and name-dropping polarity-marking standards is just dragging in a different topic to try to enhance a viewpoint. The problem is, the polarity is not the same as the voltage direction and is a separate, but related, issue.

There is nothing wrong with using polarity marking or terminal labels as a reference, but they are related to instantaneous relationships and that is a separate issue from positive voltage direction.

Again. This is usage. I have no argument with you here Mivey.

The label may be set by convention, but what is actually there is not independent of how the voltages are used. Keep in mind that the meter/scope is just a load. Using the voltages in one way shows in-phase voltages while using them another way shows two phase-opposed voltages. The meter is not lying to you because it simply shows what is really there.

Okay, here I have a mild, and I stress MILD, disagreement. What is actually there IS independent of how the voltages are used. How the voltages are used is dependent on what is actually there.

Both options are available but they are produced by a single device. You would get the same results if the voltages were produced by two phase-opposed sources. That is why I say the configuration of the source does not always define what you take from the cource. Many times the source is capable of delivering more than one output option.

Until you tie loads that change the lead/lag/angle of the voltages. Since they're the same wave on residential they compensate across both legs. With separate sources the waves won't do the same.

It is not the only point that makes sense, but it is probably the most common in the world. The grounded conductor is tied to what is essentially the world's most common reference: Earth. Power quality meters also use this as the reference instead of trying to use two difference reference points (not that there is anything "wrong" with two reference points).

I guess that would depend on your definition of phase. While we might not all be able to agree on a definiton, we should be able to agree that there are indeed two equal-magnitude real voltages available as in-phase sources or phase-opposed sources. In fact, that is simply a physical reality.

The labeling and naming conventions really should be the only ambiguity.

Agreed.

 

[SOG38]

Residential wiring known as single phase

Residential wiring known as single phase

I generally enjoy just reading the forum to see what is being discussed but I just feel a need to interject my $.02 worth.


Two-phase electrical power was an early 20th century polyphase alternating current electric power distribution system. Two circuits were used, with voltage phases differing by 90 degrees. This is what was originally generated from Niagara Falls.
The advantage of two-phase electrical power was that it allowed for simple, self-starting electric motors.
As with all poly phase systems they are derived from the generating source.
From this point the distribution systems went to Three Phase as less cost of installation was involved due to the number of wires and wire size.
When the power gets to the point of utilization then transformers are involved to bring the voltages down to site useable voltage levels.
The POCO delivers Three Phase power on the poles through their distribution. Depending on the customer they bring either Three Phases to the user in the case of an industrial customer or Single Phase to a home or small industrial user. The reality is these are transformer configurations. As the POCO distributes power going down the line they strive to balance the loads on the different lines.
For an example: They would feed all Three Phases to the industrial customer as they have many motor loads. Then as they move down the line the first non industrial customer would be fed from H1 and H2 to a Single Phase transformer to the customer?s panel supplying 240 Volts center tapped and grounded. Generally referred to as ?Split Phase? The next home would be fed from H2 and H3 followed by the next fed from H3 to H1 and on down the line attempting to balance their HV line loads.
I think from what I read the confusion is between Phasing which is a time relationship and potential which is the voltage relationship between each Phase and how the transformers are connected.

 

[pfalcon]

This is the core of the problem, this is not an absolute statement.
The 180? shift only appears when the neutral is used as the voltage reference point. Choose any of the other possible references all of a sudden the shift disappears.
Ranges and dryers are commonly used in residences, do they use the neutral as the common current carrying conductor for all of their 'internal' loads?

Since this whole thing is an exercise with a voltage divider. When using A or B as a reference you see B as 240V and any other point as identical except for magnitude. When using any other point than A or B, such as N, you see A and B with opposite polarity. And if N is not at the half mark, then A and B will be proportional. Such as 30/210 with opposite polarities.

This discussion is on par with watching a surface wave pass a fixed point. Looking left and right the waves appear to be cycling with opposing phases.

 

[pfalcon]

But if you take any other point as a common reference, you won't measure 120V to each of the other two points.

Which would be EXACTLY Jim's point. You're moving through a voltage divider, not a phase inverter.

 

[pfalcon]

It is odd how some take issue with moving one lead to measure a 180? voltage set, but have no problems moving two leads to measure the 0? voltage set. And for the players on the other team: both voltage sets are valid, real, and available voltage sets.

Agreed. As a practical issue, viewing one leg as 180? out of phase with the other can be a very good thing.

 

[pfalcon]

Any competent engineer should be able to look at Besoeker's circuit and figure it out. ...

Except I can never see his drawings for some reason

 

[Besoeker]

I already requested B to explain the working principle of his device.

From post #293:

I can, of course, explain to you how the circuit works - after all, I designed it. But would there be any point my doing so if I am, in your opinion, grossly mistaken?
In short, would you believe me?

How would you react to being called grossly mistaken over something you'd designed, seen in successful operation in a huge installed base - including India I might add.
Would it give you a nice warm, fuzzy feeling and engender a real desire to share knowledge that might be rubbished?

Anyway, although you didn't answer that post and in the interests of moving the discussion on, I'll indulge you give a potted version of how the circuit works and some of the philosophy behind it.

You will no doubt be familiar with the six pulse rectifier in both controlled controlled configurations. So, let's look at the B6C arrangement.
But here it is for reference.

With me so far?
Now, each of these six devices needs to get a shot in the arm, a tickle up the bum, once per cycle of the supply to provoke them into action.
Six pulses required over a 360deg period. One every 60deg. From a three phase supply, with phases mutually displaced by 120deg.

The 50-0-50 gave me the 180 displacement I needed for the positive and negative devices in each leg.
On the philosophy, I wasn't happy about using a naked zero crossover point for timing purposes because of dirty supplies.
So the synchronising waveform was seriously filtered. An 84 deg filter kept the karp out. And pretty much turned the sine into a cosine which is what I wanted in the first place.
Still with me?
So, comparing a DC control voltage sets the conduction angle.

There are a couple of other more subtle features.
If, for example, the supply voltage varies, the same firing angle would vary the DC output voltage from the B6C power circuit.
Closed loop systems can and do correct that.
Mine did that at a more basic level.
The cosine was directly from the supply voltage.
It drops and the comparison point between the DC control signal and the cosine advances the conduction angle without the need for control loops to kick in.

Enough....

 

[mivey]

It is surprising how you have missed the primary point of the past hundreds of postings: 'you can choose to use the neutral' versus 'you must use the neutral'.

Did not miss that. I believe I stated that I do not agree with the "must" position. Either way is perfectly valid.

Your posts tend to say that you CAN use the neutral when measuring, but that it only appears to be different for measurment purposes and is not a real physical difference. That may not be what you are trying to say but that is how it reads. The reality is that the way they are used is a real physical difference. Using Van and Vnb voltages is NOT THE SAME as using the Van and Vbn voltage set. Besoeker has proven that these can physically be two entirely different things. I understand your position is that they only APPEAR to be different things but are not really physically different. But on the contrary, the voltages taken from the transformer certainly can be configured two physically different ways and the transformer, no matter how you label it, can supply both voltage sets.

Vnb and -vnb are not two separate actual voltages, they are a single voltage with different reference points.

Using Van and Vnb voltages is NOT THE SAME as using the Van and Vbn voltage set. Two different source requirements altogether. One gives voltages with a 0? phase difference and the other a set of voltages with a 180? phase difference.

A single wiring diagram posted by Besoeker has been used to demonstrate both a shift and the lack of a shift with absolutely no wiring change. So which view is real?

Both configurations give voltages that map to the same physical space. It is the label that is the limiting factor because the label you are trying to use is not completely descriptive.

Think of a three-phase distribution circuit. If serving an essentially balanced set of single-phase loads, the source sees a three-phase load. We could also have a load-equivalent 3-phase load. Both map to the same physical space but are not the same thing.

Similarly, normal 120 volt single-phase loads might look like either loads that require a 0? source set or a 180? source set. But that is not the same thing as a 120 volt load that requires a 180? source set (like Besoeker's circuit). As loads, they may physically map to the same space but are definitely not the same thing. Conventional labeling describes one better than the other but that does not mean that only one exists.

Trying to force the issue by saying the weak label is completely descriptive of everything is like trying to fit a square peg in a round hole. The labels are just not that great but if you understand the systems, their use doesn't really hurt anything. The problem comes when some try to take these weak labels and re-write the physics behind the existing systems to make it all fit nicely: it ain't going to work because the labels just have too many inconsistencies.

I know you prefer to treat the sources as 'black boxes', but that is not always possible. There is a huge difference between wiring two transformer windings in an additive series connection, versus an open wye, or an open delta. Why not base our math on the wiring of the source instead of the wiring of the load?

Nothing wrong with using the source as a reference. I know you prefer to use the source labels as the template for the load labels but that is not the ONLY option. As I have shown with some other configurations, the source side directions and angles do not always match the resultant load side directions and angles.