three Romex sets in ceiling box

[trader_4]

There are two phases internally when the cap is in the circuit. That's why it's there, to give a phase shift. We call the motor single phase, because they run off a single phase circuit.

[trader_4]

This is what Ralph put forth:

"Two circuits were used, with voltage phases differing by one-quarter of a cycle, 90°. Usually circuits used four wires, two for each phase. Less frequently, three wires were used, with a common wire with a larger-diameter conductor. Some early two-phase generators had two complete rotor and field assemblies, with windings physically offset to provide two-phase power. "

I chose the second, three wire example and showed you how by simply changing the phase angle it becomes exactly the same as

240/120 split phase going into your house. But you deflect claiming that those are "weird" phase angles, that you can't build a generator with whatever phase angle you want, etc. I could make you two simple generators, put them on the same shaft and get whatever phase angle difference between them that I wanted by simply rotating the winding on one. Same rules, same methods, same analysis applies to any number of phases and any phase angles.

[trader_4]

The fact that a 180 deg phase difference can't be used to create a direction of rotation doesn't mean that a 180 deg phase doesn't exist. Again, if you would follow the simple questions I outlined from Ralph's old two phase 90, taking it from what everyone agrees was two phase, to other phase angles, you'd see that.

[Mark Lloyd]

I forgot the name, but there's one where the conditions say water should be solid, but it is liquid.

[Mark Lloyd]

[snip]

so are 1,4,7,10 but not 2,3,7,12.

That reminds me of the "clock arithmetic" we had in school once, where 1

- 2 = 11. It's mod12 where you say 12 when you really mean 0.

[snip]

I suppose you could if it was wound right.

[trader_4]

One more time, all you have to do is rotate the winding to get whatever phase difference you want between two generators on a common shaft. IDK why that concept is so hard.

[Clare Snyder]

That's the least of his problems - - - -

[Clare Snyder]

No - they ARE single phase - they are NOT a special case. Try to buy a 2 phase motor. They are virtually unavaolable "off the shelf" because there is SUCH a limitted market for them. Single phase motors will be used almost exclusively in those very rare locations where 2 phase power is still actually available - and they will be run on one of the two phases - just like a single phase motor in the 3 phase world. It is IMPOSSIBLE to connect a single phase motor to either a 2 phase or 3 phase circuit and have it run multi-phase - there are not enough wires!!!!

[Clare Snyder]

Would be awfulldifficult to balance both statically and under load though - - - - --

[trader_4]

And why would that be? If 90 deg isn't a balancing problem, why is rotating the winding ten more degrees suddenly a problem? Take a portable generator. If I rotated the windings, why is there suddenly a balance problem? Take a portable generator and imagine just extending the shaft to a second generator, ignoring any hp issue. I can rotate the second generator to get any phase angle, 0 to 359 degrees between it's output and the first generator's output. Now you have two phase power at any phase difference you want.

[gfretwell]

You want the rotating field to be symmetrical.

[trader_4]

Each of those generators above is symmetrical. Round and round they spin. If you mean with respect to each other, 90 deg two phase sure wasn't symmetrical. There was a winding producing 0 deg and another producing at 90 deg phase shift and seems Philly, Niagara Falls etc didn't seem to have balance problems or shake apart.... It's just how many degrees apart one winding is positioned relative to the other that determines the phase relationship.

[Clare Snyder]

Real simple. a single full turn of a generator is 360 degrees.There are 2 polarities, so a single phase reversal takes 180 degrees. Multiple phases in a single rotation need to be evenly devided.

90 degrees would produce either 2 phase or 4. deviding by 3 gives 3 phase at 120 degrees. 60 degrees gives 6 phases. 45 degrees gives 8 phase. 30 degrees gives 12 phase, and 12.5 degrees gives 16.

This refers to the OFFSET of the multiple windings in a stator, using a single bipolar rotor where the frequency is equal to RPM

Using a 4 pole or 6 pole or 8 pole rotor, etc, limits the number of phases that can be generated.the number of degrees of separation needs to be evenly devisable by the number of poles.(which MUST be an even number)

A 3 phase alternator generally uses 24 poles - but could use 12 or 6 . Being exclusively bipolar 3 cannot work

Unless you can redifine a complete revollution as something other than 360 degrees, 100 degrees can NOT work. Nor can 179 or 119 or 121.

And even 2 phase at 90 degrees would require 4 poles.

Not sure how 4 or 8 phase would even work, electrically as I suspect half of the phases would duplicate each other - - - - - -

[gfretwell]

There are 2 sets of coils displaced by 90 degrees and they look like this +

4 points on the circle. Just like 12, 3, 6, 9 on your clock. It is typically delivered on 5 wires not 3 like you would if it was L as you theorize.

[Clare Snyder]

I just figured that out as I was going through my last post - 2 phase is 4 phase - stacked

[trader_4]

I'm not theorizing, I'm simply using the example Ralph provided, the one that he claims defines two phase power:

"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 one-quarter of a cycle, 90°. Usually circuits used four wires, two for each phase. Less frequently, three wires were used, with a common wire with a larger-diameter conductor. Some early two-phase generators had two complete rotor and field assemblies, with windings physically offset to provide two-phase power. "

Are you now disputing that the second version there is not two phase power? Three wires, two hots one 90 deg out of phase with the other, a common return? Now make the phase difference 100 deg. Are there still two phases? Make it 179 deg, two phases? What about 180 deg? At 180 you have what is electrically identical to 240/120 coming into your house.

You three guys are something else. You all must have had a difficult time with algebra word problems. Problem 1, one train leaves city A at noon, headed for City B, traveling at 50 MPH. A second train leaves City B at 1:30PM, traveling at 70 MPH headed for City A. The cities are 500 miles apart, where do they meet?

Ralph: That's not a train! The only thing that can be called a train is one particular implementation of a train. They had a train in Philly

100 years ago, that's the only train allowed. There can't be trains between those cities.

Clare: The trains won't be balanced, they will shake apart

Fretwell: Those are weird speeds. You can't make one train go 50, the other 70.

Simple fact, the example Ralph provided is two phase power. And phase is not limited to 90 deg, you can make it anything you want, just rotate the second winding. Of course in physics and engineering, we don't need to create it physically at all to analyze it, we can do that on a piece of paper. We take two voltage sources:

120 Sine(wt) 120 Sine (wt+O) where O is 0 to 359

Connect them on a common return, we have three wires, the same thing as Ralph's example. Set O=180, what you have is another version of Ralph's two phase power, the same thing as 240/120 into your house, two voltage sources, 180 deg out of phase with each other.

[Ralph Mowery]

Your simple fact is wrong. For the reason as you take one of the windings and rotate it say 45 deg as you say. I don't know what it will look like or what to call it, but during part of the cycle you will have one winding 45 deg out of phase and the other 135 deg out of phase during parts of the cycle.. Really a weard wave form. You would have to add extra windings to get things to even out and may not wven be able to do that if you just give it a slight rotation of say 5 deg.

The argument is useless as there is a definition of two phase power and the split phase power as in power distribution circuits. It may very well be something else or even called something else in other countries or areas of electricity. Just as if yo go to the local lumber store and ask for a 2x4 8 feet long. The board you get will not measure 2 inch or

4 inches in any direction. Standard iron pipe will not measure what it is called either . But it is what it is by definition.

[trader_4]

What fact is wrong? I used your example of a two phase power source.

For the reason as you take one of the

Then if you don't know, maybe you should just stop right there?

but during part of the cycle you will have

Why is it not weird at 90 deg? You said that was two phase power, right? Why is it so hard to understand that I can simply rotate the winding and get whatever phase angle I want? Is it weird at 89 deg? 95 deg? That's what logical people do, it's a question a curious student trying to learn would ask a science teacher. Why is it that 90 deg is so special? Does it have to be 90? The answer of course is that it's not, it's just that was one implementation of two phase power. The general case is two power sources:

sine(wt) sine (wt+O) where O can be 0 to 359 deg

Your Philly case of 100 years ago, used O=90. That's all there is too it.

Three phase

sine(wt) sine(wt+O) sine (wt+P)

If O=P=120, then you have the three phase that's actually implemented today. But that does not mean that's the only phase angles allowed, that we can't analyze what happens at all the other possible phase angles. It's no different than the cases with differing voltages or frequencies. Yes, 72 volts, 450Hz or whatever are not implemented, but that doesn't mean that 3 voltage sources, per the above, would not have 3 phases, that it can't exist, that we can't analyze it.

Again, like the other poster tried to explain to you, *one implementation* of two phase power does not make that the definition of it. That is like saying an airplane was defined by the bi-plane, no other airplane can exist.

It may very

We're not talking about what it's called, we're talking about analyzing in electrical engineering terms, what is actually there. Again, this is like insisting that Kleenex is only Kleenex, that Kleenex is the definition and to analyze it and describe it as a soft paper product made from trees incorrect.

[Dean Hoffman]

A bunch cut.

But isn't there a point where two phase ceases to exist and becomes single phase? Wouldn't that be the point where capacitors or a start winding are needed to start motors? Practically speaking. That's what I was trying to get around to earlier.

Someone you know really well wrote this at 8:19 am on 9/12.

"There are two phases internally when the cap is in the circuit. That's why it's there, to give a phase shift. We call the motor single phase, because they run off a single phase circuit."

[Mark Lloyd]

[snip]

Why should they duplicate each outer? 2 phases don't, the same way 120 and -120 aren't even close to being the same number. Foe them to APPEAR duplicated, you'd have to be using an inconsistent point of view.

If 8 phases are evenly distributed, they'll be 45 degrees apart.