Estimating KWh electicity billing using clamp-on amp meter

[trader_4]

Since you're so smart, why don't you give us the definition of what the definition of two phase is? And note we're not arguing over what anything is routinely called, we're not arguing over what one particular implementation of two phase was a hundred years ago, we're arguing over electrically, what's there and how you do circuit analysis on it and how do you define what two phase power is in general.

Or define N phase. I have and then all phases are defined, we don't make it up as we go. And try not to use transformers, generators, or moon beams in the definition, because how it's generated doesn't matter.

[gfretwell]

It is still flowing at the same direction when you understand the concept of a circuit.

If I take your concept that every segment of a winding constitutes a phase, why not just tap that secondary twice, create 3 segments, then I have 3 phases and I can run a 3p motor.

>

[Parlor Trick]

Regarding voltage, at any instant in time, the rate of rise or fall along the entire length of the secondary coil is the same...because there is only one phase.

[makolber]

A 3 phase motor requires 3 SPECIFIC phases.... 120 degrees apart.

3 arbitrary phases will not do.

mark

[gfretwell]

Explain that to Trader. He seems to think that every time you tap a secondary you create another phase.

[trader_4]

I never said that every segment of a winding constitutes a phase, only that by center tapping it you create two phases with respect to the center point. If you make more taps, those points would be in phase with or 180 out of phase from the other taps. Again

180 out of phase is the same thing as opposite polarity in an AC circuit.

[Sam E]

[snip]

Somehow, a wiring diagram for that might help.

And 2 phases, 90 degrees apart DOES exist. It's just inside a capacitor-start motor.

[trader_4]

IDK where that came from, but I replied that if you made that tap, you'd have one coil with 240 * .66 VOLTS, the other with 240 * .33 VOLTS. The phases of the two would be exactly the same as with the center tap. You'd see two phases from the ends of the transformer with respect to the midpoint.

If a center tap transformer does not look like two voltage sources that are of opposite polarity, (out of phase by 180), then explain to us the simple electrical engineering circuit model you'd use? My model uses two 120V ideal voltage sources that are connected together, the neutral being the connection point between them. They are out of phase by 180 degrees or of opposite polarity, which is the same thing with an AC waveform. Poster Mako stated the same thing. That is how you model the 3 wire service going into the house. Explain how you draw the circuit model without two voltage sources that are 180 from each other with respect to the neutral.

[gfretwell]

I can draw it quite easily and if it is from a 3 phase source it is a delta but if it is from a single phase source it is a toaster.

The thing you can't grasp is 180 degrees out is just a different view of a single phase secondary. I really don't care anymore.

[Tekkie®]

[e-mail] posted for all of us...

I would like this discussion to phase......out

[gfretwell]

Exactly except you are simply looking at one phase, looking in 2 directions from an arbitrary point along the winding. Do you think the hands on your clock change direction at 12 and 6? After all, first they are going down, then they are going up.

[trader_4]

What you can't grasp is that how two different phases are derived, doesn't matter. The only issue is how many phases you see when you analyze it. And 240/120 is nothing more than two 120V voltage sources sharing a common neutral, one 180 out of phase from the other.

I've asked a dozen times, if instead of from a transformer the you had two 120V coils coming from a generator, two wires, sharing a common return and those coils were 120 out of phase on the shaft, would there be two phases going into the house? At 179 deg separation would there be two? How about moving one coil one more degree, what happens then? If the additional phase disappears, then I'd say that's a parlor trick. And if it doesn't then what you have going into the house from that experiment is exactly the same electrically as what is derived from the center tapped transformer. You can't tell the difference, they perform exactly the same, they are the same.

[trader_4]

Which creates TWO 120V voltage sources that are 180 deg out of phase with each other with respect to the neutral.

Do you not understand that 180 deg phase shift is the same as opposite polarity? If there aren't two phases coming into the house, why can't I parallel any two receptacles at random? It's just like with 3 phases. If I want to parallel two, I better be sure they are the same phase conductor.

Someone comes to you and asks, why can't I just parallel any two receptacles in the house? What's your answer? And the answer shouldn't involve transformers, because the answer should apply regardless of how the service is provided. My answer, there are two different phases, 180 deg apart, works regardless of how the two phases got there. Could come directly from a generator as I've cited for example many times now. Could come purely electronically synthesized off a battery, could come from an unknown black box, could come from a center tapped transformer. It doesn't matter, it;s all covered, all explained, it all looks, acts and behaves exactly the same. And it doesn't have to be 180, could be 179 deg, 90 deg, etc. It's all covered. It's the voltages, currents and phase relationships that define it, not how it was created.

[gfretwell]

Your problem is you can't step back and look at this as a system. You are locked up inside the panelboard enclosure with tunnel vision focused on the main bonding jumper like that is the center of the universe. If you look at the stars from earth, it is easy to think they revolve around the earth.

[gfretwell]

Quite simply you can't connect the ungrounded conductors together because they are at opposite ends of a 240v single phase secondary. The grounded conductor does nor even enter into it at all and there are not 2 phases at all.

[trader_4]

I can analyze it any way you like. It does not change the way the electrons are flowing in the 3 wires coming into the house and that they represent TWO voltage sources, one 180 deg out of phase with the other, or of opposite polarity if you like. Out of phase 180 and opposite polarity are the same thing in an AC system.

You

The neutral is the center of the universe, not by chance, but by design. Yet somehow you and that other guy here claim it's a parlor trick to hook up a scope and use the common point of the system as the ground, reference point, etc. And when you do that, what do you see? Two conductors, differing in phase by 180 degrees. Which of course is exactly what the electrical engineering professor with 40 years experience, consulting for utilities, presenting his paper at the power industry conference said too.

[trader_4]

Could you connect them together if they came out of a black box, where you didn't know how they were generated? Could you connect them together if the originated from a generator, with two coils separated by 180 deg? That's the beauty of consistent definitions. We define and analyze without having to know exactly how it's generated, because it doesn't matter.

Person asks, can I parallel these wires of a three phase system? My answer: Yes, if they are of the same phase, otherwise no.

Person asks, can I parallel these two receptacles in my house? My answer: Yes, if they are of the same phase, otherwise no.

What? The neutral is suddenly gone now? You can't get 120V without the neutral, except for the special, unusual case where there are loads on both sides and they are exactly balanced.

Again, that's why it's TWO voltage sources coming from the TWO halves of the transformer and why it looks like, acts like and is two voltage sources that are 180 out of phase or of alternate polarity, which is the same thing.

[makolber]

so the problem here is the power engineer guy looks at the two signals that come off the pole into your house that are 180 deg apart and/or opposite p olarity and in his mind these are ONE phase because he knows they were both derived from ONE phase of the 3 phase grid system and one is just inverted polarity of the other.

OK that is a valid view.

the signal engineer looks at the same two signals coming off the pole that are 180 deg apart and says, these are two sine waves that are 180 deg phase so it is TWO phases.

This is also a valid view.

Lets have a beer.

mark

[trader_4]

at come off the pole into your house that are 180 deg apart and/or opposite polarity and in his mind these are ONE phase because he knows they were bo th derived from ONE phase of the 3 phase grid system and one is just invert ed polarity of the other.

t are 180 deg apart and says, these are two sine waves that are 180 deg pha se so it is TWO phases.

I'm good with that. It's consistent with what I said in my first post.

[gfretwell]

No you are simply wrong. At any particular instant the current is flowing in exactly the same direction in the system. You have to look at the source. ALL of the power is coming in from the grid in the same direction at any given instant and Mr Kirchoff says the current in will always equal the current out.

You are all still trying to rationalize what you see standing in one particular spot and not looking at the whole system. Simply the fact that you think current suddenly switches direction in the same part of the cycle demonstrates that. If we assume current flows negative to positive (no I am not going to start up that fight) If L1 is negative at some particular time, current will flow from L1 towards the grounded conductor but at that same time L2 is positive and current will keep going in that same direction moving away from the grounded conductor ending up in L2. In fact the grounded conductor really has nothing to do with it when you get back to the transformer. the current is always flowing in the same direction. That is why the utility DOES NOT METER the neutral.