Estimating KWh electicity billing using clamp-on amp meter

[gfretwell]

I already did when I took your little test but it is a red herring anyway.

[gfretwell]

You can't even satisfy Kirchoffs law. You must have flunked circuits 101.

I answered that already You are connecting L1 directly to L2 and the center tap is not even involved at that time but thanks for showing us it is ONE SOURCE.

[trader_4]

ree-phase generators are built on a single shaft) so that you get two 120VA C outputs that are 180 degrees out of phase. Would it be reasonable to call this two-phase power?

tput of the transformer is single phase as well.  I don't have a two-p hase generator on my utility pole.

Well that's only because you created a bizarre theoretical situation, so a common scope that's grounded can't be used. But you can use a scope that has differential inputs. And I'd again connect it between the designated SYSTEM NEUTRAL and plot the two hots and again I'd see two sine waves out of phase by 180. You're the one trying to perform the parlor trick by not looking at the two 120V voltage source as they exist and are designed to be used, with the SHARED NEUTRAL. The shared neutral is the obvious reference point.

Electrical engineers analyzing what's there, as I have done consistently from the start. So did the elect eng prof in his IEEE paper.

And that is why there are still two phases coming from that center tapped transformer that are 180 out of phase with each other. You haven't changed what's there or how it works, only what's connected to earth.

It is just easier

Say what? If you only have 120V loads on one side of the transformer then you only have half the total rated power too. So, sure if you're willing to give up half the power, give up having 240, you can do that.

I could draw how you would hook

OMG. Having a center tap neutral isn't arbitrary, it's essential to having 240v and 120v available. It creates TWO 120V voltage sources that are 180 deg out of phase with each other, or of alternate polarity, same thing. Without that, you can't do it. It's not some accident.

And more fundamentally, I gave you the definition of N phase. It

*requires* N voltage sources of differing phase. It explains single phase, the old 90 deg two phase, a theoretical 179 deg two phase, 180 deg two phase, 3 phase, 100 phase. It's all there in that definition, without needing to refer to transformers, generators or anything else and it all is consistent and perfectly logical.

Single phase:

one voltage source sin(wt)

Two phase

two voltage sources sin(wt), sin(wt+P2)

Three phase:

three voltage sources sin(wt), sin(wt+P2), sin(wt+P3)

where P1, P2, P3 are the differing phase angles.

With 240/120, P2 is 180 With the old 90 deg two phase, it was 90

You still refuse to take the simple circuits 101 quiz because you can't explain the obvious contradictions where your argument quickly falls apart:

Test question one:

Define N phase power?

Test question two:

According to Fretwell, two phase power existed 100 years ago, and it was over two wires, 90 degrees phase difference. Suppose I run it over 3 wires instead, with a shared neutral, make it 120V. So, you have a generator supplying 120V, two coils, one shared neutral. Would there still be two phases there? (I believe Fretwell said yes) Your answer?

So now, I run that from the generator into a house, we have three wires,

120V, two phases. If I change the phase difference to 179 degrees instead of 90 by rotating one coil, are there still two phases? Yes or no?

Now I rotate it to 180 phase difference. Are there still two phases, yes or no? If you disagree, explain how it's different.

(My answer is yes and the final step above makes it absolutely IDENTICAL to what you have coming into the house with 240/120. The electrons are behaving exactly the same. )

Problem number 3

I take 3 phase power with a neutral into a house. One phase is at zero, one is at 120, one is at 240, correct? I can see them on a scope, yes?

Now I rotate one coil so that instead of 120, it's at 179. Are there still three phases?

Now I rotate it one degree more, to 180. Are there still 3 phases, yes or no?

Now take away the 240 phase. How many phases now? If it's not two, explain why.

And if it is two, then again, it's ELECTRICALLY IDENTICAL TO 240/120 servic e. IF you believe it's electrically different, explain why and how it matters in terms of the behavior of the electrons in the service conductors.

Problem number 4:

Draw the basic circuit model of 240/120 service. My model uses TWO voltage sources, with a shared neutral. One is 120V sin(wt), the other 120V sin(wt+180) or of alternate polarity connection, if you like. That is the only way to model that circuit, because that is what is there. When you center tap it, you now have TWO voltage sources. Which by the way is exactly what the professor is saying, you have two sources, 180 out of phase with each other, that's how you treat it. Do you agree with that? If not, tell us your alternate model .

Problem number 4:

Someone asks why they can't randomly parallel any two receptacles in a hous e. My answer is, because you have two 120V voltage sources that are 180 deg out of phase with each other or of alternate polarity if you like. If they were of the same phase or polarity, you could parallel them. Your answer?

See how simple and consistent it all is? And it doesn't matter if the voltage sources just exist on paper, if they are generated from a transformer, a generator, or synthesized electronically from a DC batter power source.

[trader_4]

No idea what you're talking about. If you connect two conductors that are the same voltage and the same phase angle, you've paralleled them, that's all. There is no potential difference between the two.

And again, why is it that you can't answer those simple questions, one step at a time? Never mind, I know why.

There would be all those additional sources IF YOU PROVIDED A TAP TO THEM AS PART OF YOUR CIRCUIT. Then you'd have to treat them as separate voltage sources.

You just can't easily get to

It doesn't change the fact that when you tap between batteries or tap at each cell individually, you now have created separate voltage sources and that is exactly how they must be treated. If you haven't, then explain for me the circuit model for 240/120 that doesn't use two 120V voltage sources? I've asked that 6 times now at least. And in your break into the battery at the cell level, similarly if those taps inside the battery are connected to power the circuit, then you have multiple additional separate voltage sources and they have to be treated that way.

Here are two 3 cell batteries and what you have if you tap and use all possible points:

________+ C1 ________ C2 ________ C3 ________

2C1 _______ 2C2 _______ 2C3 _______ -

You have 6 separate voltage sources and there is no other way to draw that circuit assuming you use all 6 in the circuit and if you're not then there is obviously no point to tapping them. In the transformer case, by center tapping it, you've created two 120V voltage sources that are 180 out of phase or of opposite polarity, same thing.

[trader_4]

Here's another thing that flows beautifully when you understand circuits

101 and apply it consistently. You come into your shop and your assistant Bob says, I'm going to connect these two conductors together. You look and he's fooling with some old 90 deg two phase motor, connected to a two phase power source. You shout, Bob! You can't do that, they are not the same phase!

Next day he's about to connect the 120 and 240 deg phases of a 3 phase system. You shout, Bob! You can't do that, they are not the same phase!

Next day he's about to try to parallel two receptacles that are on different hots in the 240/120 service. In my consistent world, I shout, Bob! You can't do that, they are not the same phase. You could also shout you can't do that, they are opposite polarity, which would be the same thing. What would you shout? Start talking about transformers? By the time you had just begun your tangled explanation, there would be a big explosion.

[hubops]

What colour is the sky in your world ? .. and more importantly - do you ever have time to gaze at it ? really. John T.

[gfretwell]

There is no "common scope" that isn't grounded. Certainly you can cut off the ground pin but the case of the scope will be at 120v in this scenario.

Not really. It is a single phase that starts 0-120 and continues

120-240. The reality is the current flow is exactly the same but it eliminates that confusion about one being opposite of the other.

Not really an issue since most of the load in an "all electric" house is 240v. That became very apparent to me when I was running on a generator. I did not turn off any 120v breakers and the load was still insignificant. I couldn't use many of the 240v loads, even with the

120 breakers off (no dryer, no water heater, no oven, no A/C and only one burner at a time on the cook top ) In that arrangement 240 is right there too, on a single pole breaker and single pole switching. Bod has that in his house right now as does most of the non, North American world.

The center tap is necessary but not grounding it.

I took your little quiz. Read the notes

[trader_4]

I take that to mean you can't give a definition of N phase power either.

[gfretwell]

Yes bet you are talking about 2 sources that are already connected in series in phase with each other. Then you want to simultaneously want to make a parallel connection .... Kaboom.

... I have many times. You just refuse to accept my answer.

You are just being silly now. If you can see it, it doesn't exist? No wonder the professor needs to resort to such convoluted logic to explain a simple thing to you snowflakes.

I am OUT

[Mark Lloyd]

[snip]

Such a power supply (like 2 batteries in series, with the point between them grounded) IS described as having two outputs (for example +12V and

-12V).

If the supply included a switch that exchanged the outputs periodically, you'd have phase.

[Mark Lloyd]

Strange, the argument was about what to CALL it. IIRC, nobody said anything about wiring it differently.

[trader_4]

Show us where anything I did violates it. And I can draw you the circuit diagram that models the 240/120v service. It requires TWO 120v voltage sources:

One 120v sin(wt) One 120v sin(wt+180)

Or two connected with opposite polarity, which is the same thing as 180 deg phase difference. The two 120v voltage sources are connected together at one end, sharing the neutral. THAT is your service. Where is your circuit diagram that uses only one voltage source? You can't do it, because the center tapped transformer becomes TWO separate voltage sources.

Funny how my definition of N phase power covers all phases, including this case. You can't connect the two hots together because they are differing phases. And one more time, it doesn't matter where they came from. They could come directly from a generator. What about that? The emergency power kicks in, there is no transformer. Or I power it via a UPS, electronically synthesizing two 120V waveforms that are 180 apart. That the two hots are out of phase by 180 covers it ALL.

[trader_4]

Sigh.....

The voltage on one hot is the opposite of the voltage on the other hot with respect to the neutral. We also call that 180 deg phase difference. And it works whether the TWO 120V voltage sources are from two coils on a transformer, directly from a generator, or synthesized completely electronically from a battery. It's their phase relationship, voltage and current capacity that completely define them, not how they were created. The electrons don't care, the appliances don't care.

Well, it would be a major change to the specification of the service, cutting the power available at 120V in half. How much that matters depends entirely on what all you're powering. Most houses, I would agree they don't have enough 120V loads for it to matter.

That became very apparent to me when I was running on a

Why are we even talking about what gets grounded? I didn't bring it up, you did. You wanted to earth one end of the transformer instead of the center.

I'll be looking for it.

[trader_4]

Thank you. I said that in my first post.

[trader_4]

Fretwell seems to think that providing additional taps doesn't create additional voltage sources. I keep asking for him to give us the circuit model for 240/120 service that doesn't use TWO 120V voltage sources. And that is exactly how the elect engineering professor drew the circuit, with two voltage sources.

[trader_4]

If you took it, where is it? I don't see it here.

Here it is again:

Problem 1:

Define N phase power?

Problem two:

According to Fretwell, two phase power existed 100 years ago, and it was over two wires, 90 degrees phase difference. Suppose I run it over 3 wires instead, with a shared neutral, make it 120V. So, you have a generator supplying 120V, two coils, one shared neutral. Would there still be two phases there? (I believe Fretwell said yes) Your answer?

So now, I run that from the generator into a house, we have three wires,

120V, two phases. If I change the phase difference to 179 degrees instead of 90 by rotating one coil, are there still two phases? Yes or no?

Now I rotate it to 180 phase difference. Are there still two phases, yes or no? If you disagree, explain how it's different, how there suddenly there are not two phases there.

(My answer is yes and the final step above makes it absolutely IDENTICAL to what you have coming into the house with 240/120. The electrons are behaving exactly the same. )

Problem number 3

I take 3 phase power with a neutral into a house. One phase is at zero, one is at 120, one is at 240, correct? I can see them on a scope, yes?

Now I rotate one coil so that instead of 120, it's at 179. Are there still three phases?

Now I rotate it one degree more, to 180. Are there still 3 phases, yes or no?

Now take away the 240 phase. How many phases now? If it's not two, explain why.

And if it is two, then again, it's now ELECTRICALLY IDENTICAL TO 240/120 service. IF you believe it's electrically different, explain why and how it matters in terms of the behavior of the electrons in the service conductors.

Problem number 4:

Draw the basic circuit model of 240/120 service. My model uses TWO voltage sources, with a shared neutral. One is 120V sin(wt), the other 120V sin(wt+180) or of alternate polarity connection, if you like. That is the only way to model that circuit, because that is what is there. When you center tap it, you now have TWO voltage sources. Which by the way is exactly what the professor is saying, you have two sources, 180 out of phase with each other, that's how you treat it. Do you agree with that? If not, tell us your alternate model.

Problem number 4:

Someone asks why they can't randomly parallel any two receptacles in a house. My answer is, because you have two 120V voltage sources that are 180 deg out of phase with each other or of alternate polarity if you like. You can only parallel ones that are of the same phase or polarity. Your answer?

[gfretwell]

One "hot" is 240 volts away from the other one whether you center tap the secondary or not. Do you agree with that?

[gfretwell]

It is things like this that keep me from taking you seriously,

If you have 2 windings connected end to end and they are out of phase, You have THREE PHASE DELTA, not two phase. The way you get two phase is to connect one transformer to the center tap of another. That will either look like a cross or a tee. Google up "delta vee", "Scott tee" and stop sounding ignorant of the facts. You also can't have a phase relationship more than 180 degrees (as you have theorized) because the phase rotation would change and we would be back to the complementary angle going the other way. I really suspect it would stabilize back to 120 degrees but I have never seen anyone try it, I doubt your professor has either in real life.

[devnull]

Your silly rant is moot.  You can't legally feed a single-phase meter and panel with your "two-phase" electric.

FWIW, AEP installed single-phase service into my Siemens single-phase meter box.  Even the AEP smart meter says it is single-phase.  It was inspected so it's all nice and legal.

Maybe you should take this up with AEP and let them know how incompetent they are and how they have done millions of illegal installs.

[devnull]

The typical residential transformer secondary winding is one continuous physical conductor from L1 to L2 and outputs 240 volts single-phase.  If, instead of a center tap, they installed two equally spaced taps on the secondary, you would have three 80 volt single-phase sources.