Estimating KWh electicity billing using clamp-on amp meter

[trader_4]

m end L1 toward end L2 or end L2 toward end L1.

points along the entire length of the wire at the same rate.

use there is only one phase on the single continuous piece of wire that for ms the secondary coil.

on the primary coil.  Since the primary coil is single phase, so is t he secondary.

Sure, but what happens when you center tap the secondary? You now have essentially two windings that are connected together, creating two 120V voltage sources that are of opposite polarity, which with a periodic waveform is what? ..... 180 deg phase difference. That's how you get 240/1

20 over a shared neutral. You have two 120V sources that are 180 deg out of phase.

2-phase" has any useful advantage over standard residential single phase s ervice?  Seems like pure marketing fluff.

Is the professor of electrical engineering who has 40 years experience and consults for utilities, who presented his paper at a power industry conference of his peers a marketing fluffer too? His paper directly addresses exactly this and agrees 100%, with what I said, complete with the mathematical analysis.

Note again that I answered your questions, why won;t you answer mine?

Define one phase, two phase, N phase power.

The 100 year old two phase power was with a 90 deg phase difference.

Put two windings on the same shaft at the generator and feed it to the house over three wires, shared neutral, with a 90 deg phase difference between the two coils. Would there then be two phases entering the homeowner;s house?

Yes or no?

Would there still be two phases there if I rotate one generator coil so that it's 179 deg phase difference instead of 90?

Yes or no?

If it's 180 phase difference, then what? Is that still two phases?

So I run that into a house as 240/120, how many phases now?

And if that is still two phases, then it's electrically identical to what's coming into the house from the center tapped transformer. Electrons and engineering don't care how it was created, only what is actually there.

Let's say I have a black box that has five phases coming out of it, at 120,

150, 180, 210, 240. They are electronically synthesized as you would in a uninterruptable power supply. Do you need to know what power source it uses? Why does it matter if it's powered by a DC battery, single phase or 3 phase? Is the 180 one not a legitimate phase, just because it's at 180?

The other poster raised another good point. If there are not two phases present, then I should be able to take any two receptacles in a house and parallel them. Fact is you can't, because about half are 180 deg out of PHASE with each other.

[gfretwell]

I am just disparaging his rationalization of a simple thing. The transformer in front of your house is essentially 2 windings IN PHASE that are connected together in series. The fact that they center tap it and ground the center tap might give the impression that one suddenly changed directions but it is simply not true. Lets even make this simpler for you. I have the exact same transformer and I move the ground to one end, like you see in Europe. It is a single winding with one end 2xx volts above ground. You will agree this is clearly single phase? Now how does moving the grounds back to the center change the number of phases present or change the current flow in the second half of the transformer at all? Making this 2 generators does not change a thing. If the 2 generators are in phase, hooking them in series doubles the voltage end to end but each one is still working exactly the same way. Grounding the junctions between them may look like something changed measured from the middle but nothing changed. It is my ramp again. If you are at the top, it is a ramp down. If you are at the bottom it is a ramp up but if you are in the middle it looks like 2 ramps, one up and one down. It is still just one ramp.

[gfretwell]

The current flow in those 2 secondaries is still flowing in the same direction, at the same time. Kirchoff's law says that. They did not change phase. You just changed the place where you were looking at them. Again, look at a sine wave and lay it over both windings. The 0 point will be at the center tap. One side will be up and one side down at any given instant. It is still just one sine wave and just one phase.

In "N-phase" it will be required to have "N" different sine waves but that is just a red herring in this discussion because we just have 1,

2 and 3. In each of those there is a sine wave displaced by 90 or 120 degrees.

[gfretwell]

When I read that I see him say he is talking about "modeling" not reality. My suggestion is maybe his software model needs to be adjusted to more closely reflect reality. Would you be happier if I found a half dozen articles by credentialed people who explain why this is single phase? I have certainly been in quite a few CEU seminars given by professionals who explain it in very precise terms not software models. Perhaps this is just too complicated for homeowners to grasp. That is why we say "hire an electrician".

[trader_4]

If you look at his paper, he's not rationalizing anything. He's doing a very detailed and complex analysis of how loads on the 240/120 service affect the voltage that customers receive. He starts off by explaining that what you really have are two phases there, that's how you have to model it and that's how it has to be analyzed. Then he analyzes it.

The

The center tap creates two voltage sources, with potentially two differing currents flowing in them, of opposite polarity. What is another way of saying two voltage sources are opposite polarity when they are related periodic waveforms of the same frequency? You say that one is

180 deg out of PHASE with respect to the other.

IDK why you keep going back to transformers, when it's IRRELEVANT how power is actually generated. I've said a dozen times now you could generate 240/120 going into a house from a generator with two coils, a transformer, or by synthesizing it totally electronically, or from an imaginary black box, It does not change what is there, how the currents flow, how the electrons behave.

It is a single winding with one end 2xx volts

Because now the two ends of the transformer are 180 deg out of phase with respect to your new center tap, that's how. Call it opposite polarity if you like. In electrical engineering, if you have two periodic voltage sources, one is the opposite polarity of the other, what do you call it? You say that one source is 180 deg out of phase from the other.

Why won't you just go through the simple questions, one at a time for the two problems I presented:

Problem #1:

You say the old 90 deg two phase was over 4 wires. If I instead put it over three wires, with a shared neutral, would there still be two phases? (my answer YES)

Put two 120V windings on the same shaft at the generator and feed it to the house over three wires, shared neutral, with a 90 deg phase difference between the two coils. Would there then be two phases entering the homeowner;s house?

Yes or no? (my answer YES)

Would there still be two phases there if I rotate one generator coil so that it's 179 deg phase difference instead of 90?

Yes or no? (my answer YES)

If it's 180 phase difference, then what? Isn't that still two phases? (YES)

And if that is still two phases, then it's electrically identical to what's coming into the house from the center tapped transformer. Electrons and engineering don't care how it was created, only what is actually there.

Problem #2

I have a black box that has five phases coming out of it, at 120,

150, 180, 210, 240. They are electronically synthesized as you would in a uninterruptable power supply. Do you need to know what drives it for there to be 6 phases there? (NO)

Does it matter if it came from a transformer, a generator or was synthesized using a battery? (NO)

If the 180 phase doesn't count as a phase, then why not? I can see all five on a scope. (NO)

All that is very basic stuff.

[trader_4]

ion transformer connection as single phase because from the primary side of the transformer these connections are single phase and in the case of stan dard rural distribution single phase line to ground. However, with the adve nt of detailed circuit modeling we are beginning to see distribution modeli ng and analysis being accomplished past the transformer to the secondary. W hich now brings into focus the reality that standard 120/240 secondary syst ems are not single phase line to ground systems, instead they are three wir e systems with two phases and one ground wires. Further, the standard 120/2

40 secondary is different from the two phase primary system in that the sec ondary phases are separated by 180 degrees instead of three phases separate d by 120 degrees. What all of this means is that analysis software and meth ods must now deal with an electrical system requiring a different set of al gorithms than those used

deling and analysis of the single-phase center tap transformer serving 120 Volt and 240 Volt single-phase loads from a three-wire secondary.

Good grief. It's not an issue of software modeling. It's an issue of what the circuit really is, how it really behaves. From a circuit standpoint, you don't need to know if it came from a transformer or if it came from a synthesized electronically generated source from a battery. The 240/120 service looks like TWO ideal voltage sources, that are 180 deg out of phase or equivalently, of opposite polarity sharing a common neutral. There is no other way to model it. That's all he's doing. That's what everybody does, because that's what it is, what it behaves like. If you feel otherwise, show us your alternate model.

Back to the disparaging remarks I see. And still no answers to the very simple questions a student would ask a teacher:

Define one phase, two phase, N phase power.

The 100 year old two phase power was with a 90 deg phase difference.

Put two windings on the same shaft at the generator and feed it to the house over three wires, shared neutral, with a 90 deg phase difference between the two coils. Would there then be two phases entering the homeowner;s house?

Yes or no?

Would there still be two phases there if I rotate one generator coil so that it's 179 deg phase difference instead of 90?

Yes or no?

If it's 180 phase difference, then what? Is that still two phases?

So I run that into a house as 240/120, how many phases now?

And if that is still two phases, then it's electrically identical to what's coming into the house from the center tapped transformer. Electrons and engineering don't care how it was created, only what is actually there.

Let's say I have a black box that has five phases coming out of it, at 120,

150, 180, 210, 240. They are electronically synthesized as you would in a uninterruptable power supply. Do you need to know what power source it uses? Why does it matter if it's powered by a DC battery, single phase or 3 phase? Is the 180 one not a legitimate phase, just because it's at 180?

The other poster raised another good point. If there are not two phases present, if they are not of opposite polarity, then I should be able to take any two receptacles in a house and parallel them. Instead with some combos I get 240V? Two 120V circuits with voltage waveforms that are out of phase by 180 with a shared neutral gives you exactly that.

[gfretwell]

It sounds like a software bug in his model that he is rationalizing.

Horse shit, It is still just one voltage source and the current is flowing the same way in each of them at any given instant. You are just looking at it from the middle so you get the illusion it is 2 sources. If the tap was 2/3ds the way along the secondary, would you say they were now 239 degrees out of phase?

The electrons are still moving in the same direction at the same amperage on either side of that center tap. Kirchoff says that. The only thing that differs is how much of the unbalanced load goes down the neutral but it still adds up to what goes in each end. That is why the utility only needs to measure the ungrounded leads.

If you divide a sine wave in half, it is always going to be opposite polarity on each side of the divide but it is still just one sine wave.

In fact they do and it comes over 5 wires. The windings look like this + with ground at the center. Why aren't you calling THAT 4 phase? The windings on both sides of the center tap will act just like what we are talking about.

Yes that would be 2 phase because of the phase difference between the coils but to duplicate a house service, they would need to be IN phase with each other so you would get 240v when you summed them together.

Go back to your batteries. When you connect them + to - in series, you are attaching them IN phase. The current is always flowing in the same direction and the voltage adds. If you measured them from the center it might appear they are hooked up opposite but you have to look at the system as a whole, not just one segment.

If there is truly 180 difference in current flow, the output by connecting them in series is zero. You have to look at things as a system when you connect them together, not just one small part.

[Dean Hoffman]

I guess this is as good a place as any to ask since you mentioned diesel generators. Most irrigation systems are powered by three phase 480. A lot of those are generator powered. The power unit powers the well via a power take off and also a belt driven generator on the front end. The system motors driving the towers are three phase 480. The control circuits are 120. So there's a transformer for the 120. It takes two lines of the 480 and kicks it down to 120. There is also a tap on that transformer secondary supplying 24 volts. What would you call that?

[hubops]

Omni Polly Faze.

[Morph]

It's a transformer. Single phase in yields single phase out.

All you got is a cheap parlor trick using a dual-trace scope.  Good grief!

[makolber]

this entire discussion is about semantics

for sine waves, a polarity inversion is equivalent to 180 deg phase shift.

The two operations are different, but the resulting signals are identical.

tastes great, less filling

choose one

mark

[Sam E]

[snip]

No point in the system is more than 120V away from ground.

[Mark Lloyd]

[snip]

The meaning of "phase" puts no limits on how many you can have. I have actually seen 4-phase (not for power distribution, but that has nothing to do with the meaning of "phase"). I found an article

that mentions a 6-phase system.

[Ralph Mowery]

Standard practice.

While not driven by a generator,but working off the power grid, I spent around 25 years working on and around this type of control and power system.

That 2 phase mess is going on a lot longer than the last time.

They can say whatever they want to, but there is a standard definition for the 2 phase electrical systems. The ones that do not understand that can whistle in the wind for all I care.

What's the meaning of the phrase 'A rose is a rose is a rose'? The meaning most often attributed to this is the notion that when all is said and done, a thing is what it is. This is in similar vein to Shakespeare's 'a rose by any other name would smell as sweet'. However, that's not the interpretation given by the author of the phrase.

[Mike Hunt-Hertz]

What? Have you been drinking?

[trader_4]

No it;s not. If it was just one voltage source you could not get both

120V and 240V from it. It looks, it acts like and it is two 120V voltage sources, just like if you used two 9v batteries and connected them with a center tap in between. Would there not be two voltage sources there? How would you draw the elec engineering circuit diagram for it, except with two ideal 9V voltage sources? You can't draw the diagram with a single voltage source unless you get rid of the center tap. Then it would be a single 18V voltage source. The same with the transformer as soon as it's center tapped it behaves as two voltage sources at 120V. One of the is 180 deg out of phase with the other, with respect to the neutral.

and the current is

It's not flowing in the same direction in the two hots coming into your house. When the current is flowing into the house on one hot, it's flowing out of the house on the other hot. And the current doesn't have to flow out the other hot, if it's unbalanced, some of it flows out the neutral too.

Two 9V batteries are voltage sources, yes? If I hook them in series, with a center tap between the two, do I now have only one voltage source? If so, give us the basic elec engineering circuit diagram that shows how that works. IT's obviously TWO voltage sources, just like the two halves of that transformer are two voltage source. The power engineering prof who gave that paper at the IEEE power conference is saying exactly that.

IDK where the 239 deg obfuscation is coming from. If the tap was 2/3's instead of half, you'd have one side with voltage 160V, the other with

60V.

Well that's absolutely wrong too. If the load is unbalanced, which is going to be the case almost all the time in a house, the current flowing in one half of the winding is going to be greater than the flow in the other half. Again, that's why it's TWO voltage sources with TWO different currents. The currents are only the same if it's a balanced load, which is an exceptional case.

The

Wrong. If it's unbalanced then there is more current in one half of the secondary than in the other. If 120 amps is flowing out of hot 1 and 100 amps is flowing in the opposite direction in hot 2, with 20 amps in the neutral, then you have 120 amps in one half of the secondary,

100 amps in the other half. And that is EXACTLY why the elec engineering prof who wrote that paper says it needs to be analyzed as two voltage source differing in phase by 180 deg to correctly analyze the power flows.

You are not just dividing it. You created a center tap and the two ends of transformer are now at opposite polarities, 180 deg out of phase with each other with respect to the neutral/center tap.

Make up your mind. You said many times here it was over 4 wires. And IDK what center tap you're now referring too. The example give was just generate two phases, 90 phase difference on 4 wires at a generator at 120V and run it straight to a house. I was just using the simplest example you gave, with YOUR four wires. You said that was the old

90 deg, two phase.

Who cares about 240V? It's just a simple hypothetical example, evolving one step at a time from what you said was two phase. I don't care what you do with the 90 deg phase diff hot when it gets where it's going. IT's irrelevant. The question is, if there are two phases there, apparently your answer is yes.

They are hooked up opposite from the perspective of the center tap! Your analysis is that there are not two batteries, just one. We could treat two stacked batteries that way IF there was no center tap. With the center tap they have to be treated as TWO voltage sources. Otherwise connect a lamp from the positive end of the battery on top and connect it to the center tap/neutral between the batteries. How do you analyze, how do you draw that circuit diagram without there being two diffferent voltage sources? You can't.

I note you didn't answer that question.

No, if you connect something between two different AC sources that are 180 out of phase, you get 2x the voltage. Exactly what happens when you connect a load between two receptacles inside your house that are on different hots, because they are 180 out of phase with each other with respect to the neutral.

So again, I can't analyze the output stage of an audio amplifier without going all the way back to where? The power generator?

[trader_4]

One phase 120 and then 24 volts. There is only one source conductor, one return conductor in each of those circuits, correct? In the case of 240/120 to a house we have two source conductors, one neutral return conductor, which acts as two 120V voltage sources, with one being 180 out of phase with the other, with respect to the neutral.

[trader_4]

. Introduction

The analysis of three-phase unbalanced distribution feeders normally models the load of distribution transformers at the primary terminals of the tran sformer. For single-phase center tapped transformers serving a three-wire s econdary the load will serve two 120 volt loads and a 240 volt load. The ac tual load on the transformer will be the sum of these loads. Unfortunately, the actual customer loading is generally not known so that some form of lo ad allocation will be necessary to model the load of the transformer for an alysis purposes. [

I suppose you could do the electrical engineering analysis that follows over the next several pages?

I'm sure the prof could definie N phase power without taking about two phase 90, transformers, or anything else. I did. Where is your definitio n? How can you argue about what something is, when you can't define it? I defined it:

N Phase Power - A power delivery system that uses N related voltage sources , that are periodic waveforms of the same frequency, differing only in phase.

[trader_4]

I agree!

[trader_4]

+1

I gave my definition of N phase power, no one else has:

N Phase Power - A power delivery system that uses N related voltage sources, that are periodic waveforms of the same frequency, differing only in phase.

It fits:

One phase two phase 90 two phase 179 two phase 180 three phase six phase ....