just call it 2 phase

You can have 2 phases at 90 degrees. Or you can have 2 phases at 120 degrees. Or you can have 2 phases at 109.70519 degrees. Or you can have 2 phases at
180 degrees. It's still 2 vector angles relative to the reference point, which is generally the grounded conductor. Trying to avoid referring to two phases as two phases just because their angle happens to be 180 degrees is just stubbornheadedness. If you need to specifically say what the angles are because the angles matter, then say it. But there's really no reason we can't refer to the type of power system supplying most homes in the USA as two phase power.
--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

There are three phases of distribution running around your city. A single phase goes into your neighborhood to power your home. Really I do not think there is any true difficulty caused by current nomenclature; there has not been for me. And I suspect I could come up with shortcomings and ambiguities using your proposed system as well. So, better the devil we know, because at least everyone knows it.
Have you tried using terminology like "240V, single phase, two wire, plus ground", or "240V, single phase, three wire, plus ground", or "347/600V, three phase, four wire, plus bond". Those can be shortened to "240/1phs/3W" etc. Substitute the greek 'phi' phase symbol (or a capital P in a real pinch) instead of 'phs' and it's pretty compact and explicit. 120/240V,1Phs,3W+G is not too bad.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

It is the output of a transformer winding. Regardless of the 'phase' of the primary side, the SECONDARY side is what feeds us, and it carries with is a GROUNDED center tapped secondary which means it IS single phase (only one wave movin' thru) The center tap allows us to provide protection paths. In a faulty system, they *can* provide just the opposite, but our design does make that a rare instance (San Diego Bus Stop electrocution, 2005). I think that was a 600 volt street lamp feed though. He didn't have a chance.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
| There are three phases of distribution running around your city. A | single phase goes into your neighborhood to power your home. Really I | do not think there is any true difficulty caused by current | nomenclature; there has not been for me. And I suspect I could come | up with shortcomings and ambiguities using your proposed system as | well. So, better the devil we know, because at least everyone knows | it. | | Have you tried using terminology like "240V, single phase, two wire, | plus ground", or "240V, single phase, three wire, plus ground", or | "347/600V, three phase, four wire, plus bond". Those can be shortened | to "240/1phs/3W" etc. Substitute the greek 'phi' phase symbol (or a | capital P in a real pinch) instead of 'phs' and it's pretty compact | and explicit. 120/240V,1Phs,3W+G is not too bad.
These terms are too long.
Note that I am not saying "single phase" is out. But when distinguishing between "three wire circuit where 2 wires are hot at 120 volts and are 180 degrees apart" vs. "two wire circuit where 1 wire is hot at 120 volts and degrees apart are irrelevant", I would say "2 phase" and "1 phase" (not the same as "single phase").
Got alternative SHORT names for these two systems that are clear?
--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@ipal.net wrote:

Why not just 'Edison connection'. He started a lot of this with his three-wire DC power system. It had 240 VDC between the two outside legs and 120VDC between each of those and the neutral.
I even had the 'privledge' in my early years of working on a shipboard DC generator with this third neutral leg brush set up.
daestrom
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote: | snipped-for-privacy@ipal.net wrote:
|> wrote: |> |>> There are three phases of distribution running around your city. A |>> single phase goes into your neighborhood to power your home. Really |>> I |>> do not think there is any true difficulty caused by current |>> nomenclature; there has not been for me. And I suspect I could come |>> up with shortcomings and ambiguities using your proposed system as |>> well. So, better the devil we know, because at least everyone knows |>> it. |>> |>> Have you tried using terminology like "240V, single phase, two wire, |>> plus ground", or "240V, single phase, three wire, plus ground", or |>> "347/600V, three phase, four wire, plus bond". Those can be |>> shortened |>> to "240/1phs/3W" etc. Substitute the greek 'phi' phase symbol (or a |>> capital P in a real pinch) instead of 'phs' and it's pretty compact |>> and explicit. 120/240V,1Phs,3W+G is not too bad. |> |> These terms are too long. |> |> Note that I am not saying "single phase" is out. But when |> distinguishing between "three wire circuit where 2 wires are hot at |> 120 volts and are 180 degrees apart" vs. "two wire circuit where 1 |> wire is hot at 120 volts and degrees apart are irrelevant", I would |> say "2 phase" and "1 phase" (not the same as "single phase"). |> |> Got alternative SHORT names for these two systems that are clear? |> | | Why not just 'Edison connection'. He started a lot of this with his | three-wire DC power system. It had 240 VDC between the two outside legs and | 120VDC between each of those and the neutral.
But *HE* despised AC. Additionally, what he did doesn't match all cases of what I would call "2 phase", which includes a service derived from just 2 of the 3 phases in "3 phase" that is balanced at 120 degrees.
My understanding is that his DC system was 110/220 volts, not 120/240. The exact history of electrical service and system voltages is something I am still trying to figure out. Apparently much of Europe was operating on a three phase 220/127 system, with most things connected L-L, for many years long ago. Some remnants reportedly remain in parts of Spain and Norway. So did Edison pick the voltages? Or did Tesla? Or Westinghouse? Siemens?
--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@ipal.net writes:

One thing that sets the "2 phases at 180 degrees" power separate from all the others is that you CANNOT generate polyphase power from it using a clever set of tapped transformers. Scott-T converts between 90 degree 2 phase and 3 phase. You yourself have posted how to get 3 phase power from 120 degree 2 phases with transformers. With enough transformers I can generate 19 phase power from 3 phase if I really wanted to, but not from the split phase to my house.
If you look at the resistive power (square the voltage) you can see there is no difference between single phase and Edison style 180 degree split phase. Both legs have the same power waveform. Not true for any of the other systems you mentioned, or 3 phase.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Michael Moroney wrote:

Technically speaking, it is actually two phase - phases are 360/2 degrees apart. 3 phase 360/3 degrees apart, 4 phase 360/4 etc. Also the power relationships are the same as for balanced 3 phase etc (number of phases)*Vphase*Iphase and for balanced conditions, the neutral current is 0 as in the other systems with n phases and n+1 conductors.
The statement regarding "power waveform" is meaningless- could you clarify your reasoning?
HOWEVER---- This is referred to as 2 phase ONLY in countries which don't use it. In countries that do use it - it is described as the Edison system or 120/240 single phase center tapped and Doug Young has dealt with this quite well. There is no confusion where this system is actually used
(There is what is called, in the motor world, 2 phase where the two phases are ideally 90 degrees apart. but balanced phase currents don't result in 0 neutral current )
--
Don Kelly
snipped-for-privacy@shawcross.ca
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
| phases are 360/2 degrees apart. 3 phase 360/3 degrees apart, 4 phase | 360/4 etc.
That would be the normal way of thinking of it. It gets interesting when the number of phases is any even number. For example 6 phase. I have mentioned the concept of 6 phase before and some people get confused. If a 6 phase system with phases labeled A,B,C,D,E,F (going around the circle) with phase angles of 360/6 degrees each, gives you 240 volts between A and D, then why can't a subsystem tapped from just A and D alone be called 2 phase? They are counted as 2 phases.
--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

There are a number of points of confusion.
How the system is grounded has a lot to do with the count on the number of phases. If you have three isolated center-tapped winding on an alternator or transformer bank, you can get either three or six phases very easily without changing the alternators or transformers. I worked at a place that had three-phase distribution using a V connection with the V apex grounded. That made it difficult to use unbalanced loads including those producing unbalanced harmonics arising from rectification. There was no neutral that could be used for Y connected loads.
In particular, this problem reaches into what is called two-phase. Again, with suitable windings, you could get either two-phase or four=phase. Two-phase could be looked at as four-phase with two phases missing.
This all goes to show that a true professional EE should understand what is going on without relying just upon what he learned in class.
Bill
--
Private Profit; Public Poop! Avoid collateral windfall!

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@ipal.net wrote:

That depends on how you look at it- if you bring out only the two terminals A,D you have a single voltage between them. It is then indistinguishable from a single phase 2 wire supply. With a single voltage, phase, as a relative term, becomes a problem. as what do you relate this single voltage to? If the 6 phase system is a Y rather than a polygon (super delta) then you have a neutral and then you can consider that you have a 2 phase system where the voltages Van and Vbn are 180 degrees apart. You then have 3 terminals. This is indistinguishable from the center tapped single phase system which fits what the Europeans refer to as 2 phase. Neither are distinguishable from a 2 wire single phase system if you ignore the neutral.
we are getting into "Yah, But.." territory here.
--
Don Kelly
snipped-for-privacy@shawcross.ca
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I have just come up with a magic box. I connect its to a three-phase source. I ask a technician to measure the voltages between pairs of wires leaving the output of the box. She comes up with two measurements of 120V and one of 170V. Should the Tech be fired?
The box is a Scott T transformer.
What is the point. Once you have two phases, you can build equipment that gives you anything you want. Actually, one phase (and retiurn is enough, although more complicated.
All this talk is garbage. Just stick to fundamentals!
Bill
--
Private Profit; Public Poop! Avoid collateral windfall!

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
| |> That depends on how you look at it- if you bring out only the two |> terminals A,D you have a single voltage between them. It is then |> indistinguishable from a single phase 2 wire supply. With a single |> voltage, phase, as a relative term, becomes a problem. as what do you |> relate this single voltage to? |> If the 6 phase system is a Y rather than a polygon (super delta) then |> you have a neutral and then you can consider that you have a 2 phase |> system where the voltages Van and Vbn are 180 degrees apart. You then |> have 3 terminals. This is indistinguishable from the center tapped |> single phase system which fits what the Europeans refer to as 2 phase. |> Neither are distinguishable from a 2 wire single phase system if you |> ignore the neutral. | | I have just come up with a magic box. I connect its to a three-phase | source. I ask a technician to measure the voltages between pairs of | wires leaving the output of the box. She comes up with two measurements | of 120V and one of 170V. Should the Tech be fired? | | The box is a Scott T transformer. | | What is the point. Once you have two phases, you can build equipment | that gives you anything you want. Actually, one phase (and retiurn is | enough, although more complicated. | | All this talk is garbage. Just stick to fundamentals!
Fundamnetally, Edison did not contribute to AC.
Fundamentally, you can have a reference terminal, and 2 power terminals with AC output at some fixed frequency. If you have controls to change their phase angles, you still have 2 of them, even if you happen to adjust them to exactly 180 degrees apart.
--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Salmon Egg wrote:

Correct <if> you look at the voltages with respect to the T junction- assuming it is available external to the box-there is no reason for it to be so. There is another set of terminals so 3 more voltage pairs can be measured- the 3 phase input. The technician should be fired for not measuring the voltages between the supply terminals but more importantly not measuring the <output> voltage as specified. The voltages from the T junction are not the output. If you look at the <output> terminals, you will have two sets of voltages in quadrature -2 phase- and the result will be two equal voltages in quadrature.

--
Don Kelly
snipped-for-privacy@shawcross.ca
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Don Kelly wrote:

**************** Apologies- my statements above are arrant nonsense. The only excuse that I have is that I was distracted by the wind whistling between my ears as when I went to bed and blocked the wind with a pillow, it became obvious that I blew it.
--
Don Kelly
snipped-for-privacy@shawcross.ca
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
| snipped-for-privacy@ipal.net wrote:
|> |> | phases are 360/2 degrees apart. 3 phase 360/3 degrees apart, 4 phase |> | 360/4 etc. |> |> That would be the normal way of thinking of it. It gets interesting when the |> number of phases is any even number. For example 6 phase. I have mentioned |> the concept of 6 phase before and some people get confused. If a 6 phase |> system with phases labeled A,B,C,D,E,F (going around the circle) with phase |> angles of 360/6 degrees each, gives you 240 volts between A and D, then why |> can't a subsystem tapped from just A and D alone be called 2 phase? They are |> counted as 2 phases. |> |> | That depends on how you look at it- if you bring out only the two | terminals A,D you have a single voltage between them. It is then | indistinguishable from a single phase 2 wire supply. With a single | voltage, phase, as a relative term, becomes a problem. as what do you | relate this single voltage to?
If you have a neutral or ground or some kind of ground reference, even if high impedance, then you have 3 points, 2 or 3 vectors, and can determine an angle. If you don't, all you have is the voltage difference.
| If the 6 phase system is a Y rather than a polygon (super delta) then | you have a neutral and then you can consider that you have a 2 phase | system where the voltages Van and Vbn are 180 degrees apart. You then | have 3 terminals. This is indistinguishable from the center tapped | single phase system which fits what the Europeans refer to as 2 phase. | Neither are distinguishable from a 2 wire single phase system if you | ignore the neutral.
Is it standard in Europe to use "2 phase" to refer to what Americans mostly use some variation of "Edison style split single phase"?
I don't like to call any AC system based on Edison in any way. Edison did not design around AC. He did DC. Thus he didn't split his power system in any way considering angles, because there were no angles. Edison would not recognize the power system coming into my home. Tesla might.
And Edison is quite far from being my favorite inventor/scientist/engineer.
--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote: <snip>

Au contrarie, Edison might look at the three wires, measure 120/120 and 240 and say, "Gee, that's pretty much how I did it except you're using that 'deadly' AC crap!"
daestrom
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
|
| wrote: | <snip> |> Is it standard in Europe to use "2 phase" to refer to what Americans |> mostly |> use some variation of "Edison style split single phase"? |> |> I don't like to call any AC system based on Edison in any way. Edison did |> not design around AC. He did DC. Thus he didn't split his power system |> in |> any way considering angles, because there were no angles. Edison would |> not |> recognize the power system coming into my home. Tesla might. | | Au contrarie, Edison might look at the three wires, measure 120/120 and 240 | and say, "Gee, that's pretty much how I did it except you're using that | 'deadly' AC crap!"
And, of course, that was Edison's downfall from being a big supplier of electric power to the country. But had he accepted AC back in those days, I believe it would have had much more influence on what we have today as electrical systems than anything we could possibly do today. If he had stepped AC down to 10 volts at the light socket, he would have been able to make electricity safer (because the light socket was the most dangerous part, being right up near where people worked), but also made his light bulbs more reliable (lower voltage means a thicker filament). His goal wasn't to sell light bulbs in greater quantity. His goal was to sell electric service as a replacement for gas lighting.
--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Ah he was smarter than that. Let's see, you want to put a small transformer in every light fixture so that he won't sell as many light bulbs. General Electric (which at one time was Edison's company IIRC), sold lightbulbs by the millions.
Considering that few people are conversant with total cost of operation, they would have looked at Edison's more expensive light sockets and opted for someone else's product line.
daestrom
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
|
| wrote: |> | <snip> |> |> Is it standard in Europe to use "2 phase" to refer to what Americans |> |> mostly |> |> use some variation of "Edison style split single phase"? |> |> |> |> I don't like to call any AC system based on Edison in any way. Edison |> did |> |> not design around AC. He did DC. Thus he didn't split his power |> system |> |> in |> |> any way considering angles, because there were no angles. Edison would |> |> not |> |> recognize the power system coming into my home. Tesla might. |> | |> | Au contrarie, Edison might look at the three wires, measure 120/120 and |> 240 |> | and say, "Gee, that's pretty much how I did it except you're using that |> | 'deadly' AC crap!" |> |> And, of course, that was Edison's downfall from being a big supplier of |> electric |> power to the country. But had he accepted AC back in those days, I |> believe it |> would have had much more influence on what we have today as electrical |> systems |> than anything we could possibly do today. If he had stepped AC down to 10 |> volts |> at the light socket, he would have been able to make electricity safer |> (because |> the light socket was the most dangerous part, being right up near where |> people |> worked), but also made his light bulbs more reliable (lower voltage means |> a |> thicker filament). His goal wasn't to sell light bulbs in greater |> quantity. |> His goal was to sell electric service as a replacement for gas lighting. |> | | Ah he was smarter than that. Let's see, you want to put a small transformer | in every light fixture so that he won't sell as many light bulbs. General | Electric (which at one time was Edison's company IIRC), sold lightbulbs by | the millions.
Edison was not making light bulbs to sell light bulbs. If that were the case, he wouldn't have done what it did to actually try to extend the life of them. Remember, he did not invent the light bulb. He just improved on it. Instead, he was trying to create a greater demand for electricity than existed for a few motors here and there at the time.
| Considering that few people are conversant with total cost of operation, | they would have looked at Edison's more expensive light sockets and opted | for someone else's product line.
Either way, the business model was on creating a demand for electricity and selling an incrementally priced service. He would not have the market locked up on light bulbs for very long. His goal was the electric service business which would be a monopoly where it was deployed.
--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.