Singlephase 240V

[Smart $]

... Perhaps some time spent in the audio world would broaden their minds.

...

Broaden... likely.

Change of perspective, perhaps at best.

Yet the audio world has its own share of both jargon and buzz words. For instance, a similar but likely lower voltage supply in the audio [electronics] world is generally called a dual or split voltage supply... seldom making any reference to phasing, mostly because such an AC supply is rectified, filtered, and regulated into DC voltages for the signal level components.

 

[gar]

090908-0703 EST

Smart $:

My 1962 Sola CVH 23-22-112 name tag titles the device as Constant Voltage Transformer.

Power Conditioner is a recent marketing gimmick. Although it might include more than the basic constant voltage transformer.

US patent 2,694,177 filed 16 March 1951 and issued 9 Nov 1954, and 2,806,199 numbers are listed on my transformer. The original patent is 2,143,745 filed 31 August 1938 and issued 10 January 1939 . In the original patent it was listed as Constant Potential Transformer.

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[LarryFine]

Why do you think timing is a factor?

No, I said it isn't. 180 degrees out of phase is timing. Opposing simultaneous peaks is polarity.

The timing is really not relevant past the first 1/2 cycle and really only matters in the audio (or similar) world. We are not talking about a delayed signal anyway.

Actually, I am very familiar with audio. A center-tapped secondary is often used as what's called a phase splitter for converting a single-ended signal into a push-pull signal, but it's a polarity thing, not a timing thing.

Two separate but opposite signals will peak simultaneously but that does not mean it is only a matter of polarity. In this case, it just so happens that a polarity change and a 180 degree difference are the same thing (again, we are not talking about time delays).

And again, I say that they resemble, but are not the same thing. If the 180-degree "shift" is one setting of a variable, then I might agree. But, the 180-degree difference is locked by the primary being single-ended, a single source.

 

[mivey]

No, I said it isn't. 180 degrees out of phase is timing. Opposing simultaneous peaks is polarity.

Actually, I am very familiar with audio. A center-tapped secondary is often used as what's called a phase splitter for converting a single-ended signal into a push-pull signal, but it's a polarity thing, not a timing thing.

And again, I say that they resemble, but are not the same thing. If the 180-degree "shift" is one setting of a variable, then I might agree. But, the 180-degree difference is locked by the primary being single-ended, a single source.

But you are linking timing with a difference in phase so you are saying timing is relevant when talking about a phase difference. You can have a phase difference without having a time shift (or phase shift) like you might have in the audio world. With our 180 degree difference, there is no missing 1/2 cycle at the beginning of one of the waveforms and no extra 1/2 cycle at the other end.

There is no phase/time shift that produces the 120 degree phase difference and there is no phase/time shift that produces the 180 degree phase difference.

You can have a 180 degree phase difference created by more than one source. You can have 3 phases created by one source, although the single source would be run through more than simple transformers.

If I hide the source from you, you would not be able to tell me how I created the two waveforms with a 180 degree difference. The method used to create the system doesn't necessarily define the created system, although the method can limit what I can create.

 

[LarryFine]

But you are linking timing with a difference in phase so you are saying timing is relevant when talking about a phase difference.

I am.

You can have a phase difference without having a time shift (or phase shift) like you might have in the audio world.

Like the push-pull circuit, you mean? Yes, it's called a phase splitter, and we understand why, but it really is a polarity inverter, just like an active phase splitter.

One could use a 1:1 transformer to invert a phase, but it, too, is really is a polarity inversion. You couldn't use one to synthesize another phase, just an inverted one.


Apparently, I associate poly-phases with time, or time lapse, and not just an "is it additive or subtractive?" perspective. Look at the two-batteries-in-series case again:

If you ground the negative end, it's a dual-voltage (yet single-polarity) supply, but if you ground the center point, it's a bi-polar supply. All with no other changes.

With our 180 degree difference, there is no missing 1/2 cycle at the beginning of one of the waveforms and no extra 1/2 cycle at the other end.

Which, to me, strengthens the argument that a genuine phase shift (timing difference, whichever) requires that missing half cycle. Genuine phase shift requires time.

Let's say we had a device that can alter phase of an AC voltage, and dial it anywhere from 0 deg thru 90 deg leading thru 180 deg thru 90 deg lagging, and back to 0 deg.

In my opinion, when it's at 180 degrees, relative to the input, it is indeed a 180-deg phase shift, and it also becomes a polarity inversion, but there's a difference:

The output is being compared to the input. With the secondary of a single phase transformer (where we agree we don't care about the primary), there's no outside reference.

In other words, I don't agree (technically speaking) that one half of the winding is out of phase with the other half. It can't be, because it's a single winding, center tap aside.

I agree that it resembles a 180 deg shift, but it ain't one. That's how I see it.

There is no phase/time shift that produces the 120 degree phase difference . . .

To me, there is, starting with the physical 120 degrees between the phase windings on the alternator.

. . . there is no phase/time shift that produces the 180 degree phase difference.[/i]

There, I agree.

You can have a 180 degree phase difference created by more than one source. You can have 3 phases created by one source, although the single source would be run through more than simple transformers.[/i]

Absolutely.

If I hide the source from you, you would not be able to tell me how I created the two waveforms with a 180 degree difference.

No, but I would know that you had two sources. A transformer winding is a single source. It's two batteries in series that keep simultaneously flipping over in their holders.

You could have two single-battery holders or one two-battery holder with a tap, but you must flip the batteries simultaneously. I that case, I couldn't tell which.

But, I could tell you had a single source (group) because the total voltage is always twice that of one battery, or always "180 deg out of phase." You're only swapping polarity.

You'd need two independent sources which happened to be at 180 deg, relatively speaking, to actually have an out-of-phase voltage source; it has to be out of phase with something.

One source is always "in phase" with itself, no matter how many connections it has. If you want to use the center tap as your reference, go ahead, but there's only one "phase."



I have no idea how much sense this is all making, but it sure is fun.

 

[Smart $]

090908-0703 EST

Smart $:

My 1962 Sola CVH 23-22-112 name tag titles the device as Constant Voltage Transformer.

Power Conditioner is a recent marketing gimmick. Although it might include more than the basic constant voltage transformer.

US patent 2,694,177 filed 16 March 1951 and issued 9 Nov 1954, and 2,806,199 numbers are listed on my transformer. The original patent is 2,143,745 filed 31 August 1938 and issued 10 January 1939 . In the original patent it was listed as Constant Potential Transformer.

.

I'm not all that concerned about it.

Regardless of what it contains or is called, your experiment was not indicative a true split phase output... and it really doesn't qualify as a near equivalent circuit because you used two non-identical "transformers". As for a time-shifted output signal, it really doesn't matter how it is generated or derived... it is what it is.

 

[mivey]

Which, to me, strengthens the argument that a genuine phase shift (timing difference, whichever) requires that missing half cycle. Genuine phase shift requires time.

We are in agreement on that. I am not saying we have a time shift.

In other words, I don't agree (technically speaking) that one half of the winding is out of phase with the other half. It can't be, because it's a single winding, center tap aside.

I agree that it resembles a 180 deg shift, but it ain't one. That's how I see it.

I am making a distinction between a phase shift and a difference in phase angles. I agree that it ain't a time shift. To me, in this case, out of phase is not meaning a time shift but that the waveforms go from negative to positive at different points in time.

There is no phase/time shift that produces the 120 degree phase difference...

To me, there is, starting with the physical 120 degrees between the phase windings on the alternator.

And I would argue that for a 120 degree separation, all three waves start at the same time. In the 180 degree case, from a dead start, one wave starts going positive at the same exact time that the other starts to go negative. This is not a phase shift (or time shift), but two voltages that have a 180 degree difference. These two waveforms fit the general definition of a n-phase system where n=2 and you have a 360/2=180 degree displacement.

No, but I would know that you had two sources. A transformer winding is a single source.

There would be no way for you to tell if I had two independent sources that were synchronized to have a 180 degree phase difference or if I had center-tapped a single-source transformer.

You'd need two independent sources which happened to be at 180 deg, relatively speaking, to actually have an out-of-phase voltage source; it has to be out of phase with something.

One source is always "in phase" with itself, no matter how many connections it has. If you want to use the center tap as your reference, go ahead, but there's only one "phase."

Whether I have two independent sources or one source, I will have created two voltages with a 180 degree difference. Phase-shifting aside, the method of creation does not matter, only the created waveforms.

 

[gar]

090908-2040 EST

Consider a black box. Two input terminals called Hot and Neutral supplied with a single phase 60 Hz sine wave. Three output terminals called C (common), A, and B. For convenience, internally the input Neutral is connected to the output Common. This is so we have a common point for an oscilloscope.

We assume that whatever is inside the black box produces output sine waves of exactly the same frequency as the input and are phase locked to the input, but possibly adjustable in the phase lock relationship to the input.

If you look at various definitions for phase difference, phase meters, phase offset, or other similar descriptions the end result is that primarily a periodic waveform is assumed, meaning repetition of a pattern that occurs at a uniform displacement for a period of the waveform. This displacement may be measured as an angle as is often the case for a sine wave. Knowing the frequency of the period of the waveform that angle can also be described as a time displacement. If you have graphs on a piece of paper the displacement could be in inches.

Phase difference between the waveforms is defined as the displacement from a point on one waveform to a corresponding point on the other waveform. This could be from a positive slope zero crossing of one waveform to a positive slope zero crossing on the other waveform. You would probably limit the range to one period. This has nothing to do with a time displacement of the waveforms, but could be measured in terms of time.

Back to the black box.

If inside the box is a center tapped transformer and the center tap is connected to terminal C, then A to C is an inversion of B to C. The phase difference between the two is also 180 deg.

Instead of the transformer inside the box there are two phase locked oscillators with full adjustment of the phasing of each. Oscillator A is synced to the input line to be in phase with the input line. Oscillator B has adjustable sync from 0 to 360 deg.

When oscillator B is set to zero phase the two outputs A and B are inphase and appear equal to each other, and the phase difference is 0.

Next adjust B to a 90 deg phase. Now the positive peak of B corresponds to the negative slope zero crossing of A.

Further adjust B to a 180 deg phase and its negative peak corresponds to A's positive peak. Some literature refers to this as an antiphase as well as a 180 deg phase shift.

Why should a 179.9999999999999 deg phase shift be called a phase shift and not also call 180.0000000000000 a 180 deg phase shift.

When you have no information about the contents of the black box, then you have to base your description on the output signals that can be measured. I do not have measuring capability to resolve 0.0000000000001 in phase difference. Therefore I can not decide if the signal is inverted or shifted.

Why should there be a discontinuity in describing phase shift at exactly N*180 deg?

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[mivey]

...Why should a 179.9999999999999 deg phase shift be called a phase shift and not also call 180.0000000000000 a 180 deg phase shift.

When you have no information about the contents of the black box, then you have to base your description on the output signals that can be measured. I do not have measuring capability to resolve 0.0000000000001 in phase difference. Therefore I can not decide if the signal is inverted or shifted.

Why should there be a discontinuity in describing phase shift at exactly N*180 deg?

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I kept thinking because someone had heard in audio you make a distinction between a difference in polarity vs a time shift that results in a 180 degree phase shift (i.e., the missing 1/2 cycle at the beginning and ending of the signals). I thought if someone knew enough about audio they would know that this is not what we are talking about.

Now I'm not sure what the hang-up is.

 

[LarryFine]

I guess my hang-up is that, while I'll agree that A-C and B-C have a 180 deg relationship, the source is a single phase source, and that's the discussion.

We can describe 120/208v 1ph as "two phases of a 3-phase system," but I don't feel that we can call 120/240v 1ph "two phases of a 1-phase system."

 

[mivey]

I guess my hang-up is that, while I'll agree that A-C and B-C have a 180 deg relationship, the source is a single phase source, and that's the discussion.

And I was focusing on the waveforms and how they can fit the general polyphase definition.

We can describe 120/208v 1ph as "two phases of a 3-phase system," but I don't feel that we can call 120/240v 1ph "two phases of a 1-phase system."

LOL. I sure wouldn't.

 

[Smart $]

And I was focusing on the waveforms and how they can fit the general polyphase definition.

But you have to invert one of the waveforms for it to fit

 

[mivey]

But you have to invert one of the waveforms for it to fit

Invert? Relative to what? If I have not previously established a reference point, I have not inverted anything.

 

[Smart $]

Invert? Relative to what? If I have not previously established a reference point, I have not inverted anything.

Defensive to the end, eh?

 

[mivey]

Defensive to the end, eh?

No, I really did not follow you.

In the 180 degree case, the reference is the neutral and you use the voltage the lines to get the two 120 volt values.

In the 0 degree case, you can use one line as a reference and use the neutral and other line to get 120 volts and 240 volts, or use two different references (one line, the other the neutral) to get two 120 volt values.

I don't see what is inverted. Unless you are trying to compare two systems that are using different references and I'm not sure that qualifies as an inversion.

I would see an inversion if you were to establish a reference point first and get some reference values, then swap terminals to invert the reference values.

 

[mivey]

Think about what is going on with the loads. A 3-phase delta supply delivers 3 waveforms with 3 different angles (120 degree separation).

A historic 2-phase supply delivered 2 waveforms with two different angles (90 degree separation). This was sometimes seen as two separate single phase supplies. It was also seen as a subset of a 4-phase system with 4 different angles (90 degree separation). In the 4-phase case, two of the phases were opposite in polarity to two of the other phases. The opposite polarity and 180 degree difference is the same thing for this system. This is documented historically so should not cause anyone heartburn.

Just because two of the waveforms were opposite in polarity to two others did not invalidate it as a 4-phase supply. What made it a 2-phase supply was when only two waveforms were used, like with a 2-phase motor.

That is what makes the number of phases: the number of waveforms with different angles. To be considered a regular system, the waveforms would have angles such that they are evenly dispersed around a 360 degree circle. The historic 2-phase was viewed as an irregular system.

Had we took a historic, 90-degree, 3-wire 2-phase supply and connected a load line-line, we would have been using it as a single phase supply. This is the same as what we do when we connect a load at 208 volts on a 120/208 volt supply. We are using it as a single phase supply. The same is true if we connect a load line-line on a 3-phase supply.

The 120/240 center-tapped transformer is used as a single phase supply with individual 120 volt loads and with 240 volt loads. But, if we were to use it to supply a load that used both line-neutral voltages, it could also been seen as a 2-phase supply. The opposite polarity does not invalidate the 2-phase just as it did not invalidate the opposite polarity in the 4-phase supply. If one holds true the other must hold true.

I just think we tend to supply single-phase loads with the center-tapped transformer. I supposed we could think of a case where both line-neutral voltages are used for a device.

The historic 2-phase supply was actually using both phases for a 2-phase motor. A 2-phase motor with a 180 degree displacement supply would probably not be worth much. But, if we did find a load that needed a 180 degree displaced 2-phase supply, the center-tapped transformer could do just that.

 

[hurk27]

I have been reading this, and trying to figure out how you guys are relating the 180? of a single winding with the 120? rotational offset of three windings of a 3-phase generator?

the two are not the same, one is the ac sine wave relationship between the ends of one winding (or pole) and the other is the relationship of the rotational offset in degrees of any two windings at a given point in time, the reason we have single phase is because anytime you connect to a 3-phase delta system between just 2 points , only one winding of a generator is supplying the load, thus the 180? you see from one one circuit conductor to the other, this has no relationship to the 120? phase angle when all three phases are used.

If we were to take a single phase 240v generator and series it with another, and use one more to close the delta, now connect each shaft so that each is 120? in rotation from each other, we can see the 120? relationship is only the rotational relationship, but each winding is still 180? out of phase with each end of this one winding, so when we apply a load, only one winding supply's the load.

We call this one winding a phase, or a pole, Hence 2-pole, 3-pole breakers, but since we are only using one pole/phase of the generator we call it single phase.

Also it has nothing to do with the neutral of single phase a center taped transformer, the two windings of a center tap transformer are just a series circuit that has a 180? relationship with each end or with each end and the center tap, there is no 90? off set to the neutral or it just wouldn't work.

A 4-wire delta is a different animal because all three phases are involved when using the B to neutral connection, and one must consider the 60? offset. this is the same with a Y, but the OP was asking about a delta or 240 volt system.

let me know if I have this wrong?

 

[mivey]

I have been reading this, and trying to figure out how you guys are relating the 180? of a single winding with the 120? rotational offset of three windings of a 3-phase generator?

the two are not the same, one is the ac sine wave relationship between the ends of one winding (or pole) and the other is the relationship of the rotational offset in degrees of any two windings at a given point in time, the reason we have single phase is because anytime you connect to a 3-phase delta system between just 2 points , only one winding of a generator is supplying the load, thus the 180? you see from one one circuit conductor to the other, this has no relationship to the 120? phase angle when all three phases are used.

If we were to take a single phase 240v generator and series it with another, and use one more to close the delta, now connect each shaft so that each is 120? in rotation from each other, we can see the 120? relationship is only the rotational relationship, but each winding is still 180? out of phase with each end of this one winding, so when we apply a load, only one winding supply's the load.

We call this one winding a phase, or a pole, Hence 2-pole, 3-pole breakers, but since we are only using one pole/phase of the generator we call it single phase.

Also it has nothing to do with the neutral of single phase a center taped transformer, the two windings of a center tap transformer are just a series circuit that has a 180? relationship with each end or with each end and the center tap, there is no 90? off set to the neutral or it just wouldn't work.

A 4-wire delta is a different animal because all three phases are involved when using the B to neutral connection, and one must consider the 60? offset. this is the same with a Y, but the OP was asking about a delta or 240 volt system.

let me know if I have this wrong?

I am considering the waveforms, not getting bogged down with the number of windings or how the waveforms were created (could be no windings). Forget the windings, because the number of phases is the number of waveforms with different angles.

We call it single phase when we only have one angle.

A 4-wire delta is a combination of a 3-phase supply and a single phase supply.

 

[mivey]

Also it has nothing to do with the neutral of single phase a center taped transformer, the two windings of a center tap transformer are just a series circuit that has a 180? relationship with each end or with each end and the center tap, there is no 90? off set to the neutral or it just wouldn't work.

I have re-read your post several times and it appears you are saying one end of a winding is 180 degrees out of phase with the other end. You must have a reference point if you are going to say a point has a certain voltage. The end alone is not a voltage because you need two points to establish a potential.

Once you establish the first potential, you can assign it an angle and then you can talk about the angle of other potentials relative to the first potential.

 

[gar]

090910-0752 EST

mivey:

Your posts 76 and 79 are excellent.

.