May I ask a question about the single vs two phase stuff

[mivey]

I'll just remind people (yes, this has already been discussed) that standard industry nomenclature (at least in the US) is that a phase is a combination of two line conductors with a voltage. A neutral does not count.

That is no standard. That is a proposal by one of the members here but also has its own set of conflicts with names.

That's why even a 120/208 service is referred to as single phase by utilities.

Not universally, not even historically accurate.

You can discuss the adjectival 'in phase' and 'out of phase' and 'anti-phase' as much as you like, but a 'phase' (noun) actually has a consistent industry meaning in this country.

Not even close.

 

[Besoeker]

Back to exactly what you are comparing to what?

One phase with another with respect to a common reference.

 

[mivey]

The definition 240/120V is single phase supply is used by POCO in practice. Who uses the other definition in practice? Answer: None.

It is an understanding of what is happening and fundamental concepts. Nothing says you have to understand anything beyond what you are used to or anything complicated. Reader's choice to keep life as simple as they want it.

Here we tend to explore beyond the mundane because it is more interesting.

 

[Sahib]

It is an understanding of what is happening and fundamental concepts. Nothing says you have to understand anything beyond what you are used to or anything complicated. Reader's choice to keep life as simple as they want it.

Here we tend to explore beyond the mundane because it is more interesting.

Only the definition 240/120V is single phase supply is found in technical literature. Even OP article states so. So state at least one technical reference that supports your views.

 

[jaggedben]

That is no standard. That is a proposal by one of the members here but also has its own set of conflicts with names.

Not universally, not even historically accurate.

Not even close.

I think you really need to show the counterexamples, not just make an assertion. What utilities in this country don't follow what I said?

 

[mivey]

Only the definition 240/120V is single phase supply is found in technical literature. Even OP article states so. So state at least one technical reference that supports your views.

I have posted pages of technical references. I don't feel like doing it all over again. Feel free to read my prior posts.

 

[mivey]

I think you really need to show the counterexamples, not just make an assertion. What utilities in this country don't follow what I said?

Not assertions. I have posted examples many, many, many times.

If there is one thing I have learned in these many postings and threads, in which I have posted hundreds of examples and have dedicated hundreds and hundreds of posts, posting them over and over makes little difference to some.

Come up with something new and we can talk about that.

 

[jaggedben]

Not assertions. I have posted examples many, many, many times.

If there is one thing I have learned in these many postings and threads, in which I have posted hundreds of examples and have dedicated hundreds and hundreds of posts, posting them over and over makes little difference to some.

Come up with something new and we can talk about that.

If you had posted e.g. a link to a utility document or website that referred to a 120/208 service as 'two phase', I'm pretty sure I'd remember that.

I stand by my previous post.

 

[mivey]

Not assertions. I have posted examples many, many, many times.

If there is one thing I have learned in these many postings and threads, in which I have posted hundreds of examples and have dedicated hundreds and hundreds of posts, posting them over and over makes little difference to some.

Come up with something new and we can talk about that.

If it helps, many utilities and references refer to 120/208 as a network supply and also as a subset of a three phase supply where one phase is missing.

And FWIW, a single phase supply consisting of one line conductor and one neutral conductor is not called a zero phase system. Again, the definitions can vary and more than one definition can be valid. There are many ways to define phase and you will find references to support multiple definitions.

The names are not complete physical descriptions of a system. They are just names.

 

[mivey]

If you had posted e.g. a link to a utility document or website that referred to a 120/208 service as 'two phase', I'm pretty sure I'd remember that.

I stand by my previous post.

Then stand as you wish. No facts can change your mind if you don't want to change it.

No harm done, we are pretty much where we were before the discussion started.

 

[Sahib]

I have posted pages of technical references. I don't feel like doing it all over again. Feel free to read my prior posts.

Show at least one solid technical reference.

 

[mivey]

Show at least one solid technical reference.

Been there. Done that. Many times. It will make no difference.

I've posted some references in this thread. I've posted many more in other threads. There is always a "but" added for those that can't accept something different than what they understand/like. You can either accept that there are multiple definitions of phase or not. You can accept their basis or not.

Or, like me, you can accept each definition in its own right without having to universally dismiss other definitions that differ. I prefer to understand the basis for each and the caveats that go with them.

To repeat:

Not assertions. I have posted examples many, many, many times.

If there is one thing I have learned in these many postings and threads, in which I have posted hundreds of examples and have dedicated hundreds and hundreds of posts, posting them over and over makes little difference to some.

Come up with something new and we can talk about that.

Because of the way it is normally used. 120/240 or 120/208 normally serve single-phase loads so that becomes the common name.

The name is just a name and not a physical description. It has a basis but not completely descriptive of the system.

Physically, the two-phase system is just a specific subset of the four-phase system and so the 5-wire two-phase is more correctly called a four-phase system. It was used to provide two phases so the name sticks. How about some history? There are too many for me to feel like putting them all here again but here are some quotes for you on names and about a 180d phase difference:


From the article "The Design and Action of the Rotary Converter" in Engineering Magazine vol 22, by David Rushmore, 1917




From: "Engineering Circuit Analysis", William Hayt, 1962, McGraw-Hill, pg 572:



From "Alternating Current Machines", Sheldon, 1902:



From: "Center-Tapped Transformer and 120-/240-V Secondary Models" William H. Kersting:



From "Techniques of Circuit Analysis" by Carter/Richardson concerning forming polyphase sources from voltage sources separated by phase angle differences:



From "Photovoltaic Power Systems and The National Electrical Code", Sandia National Laboratories:

 

[Sahib]

I referred to Hayt's book and found that your views are exactly as stated therein. Superb.:thumbsup:

 

[mivey]

I referred to Hayt's book and found that your views are exactly as stated therein. Superb.:thumbsup:

My hat off to you for doing some research. How refreshing. :thumbsup:

With more study you will find references for both. The trick is understanding how both positions/definitions are valid in their own right and how they both are physically possible.

You have two type systems that map to the same physical space so you can take either back out from that same physical space.

 

[mbrooke]

I think I missed it- but do these books have links?

Edit- guess I am asking if they are free to look at.

 

[mivey]

I think I missed it- but do these books have links?

Edit- guess I am asking if they are free to look at.

Not sure. Google and other resources have many old books from late 1800's to early 1900's scanned. The newer ones are probably only in print.

 

[mbrooke]

Not sure. Google and other resources have many old books from late 1800's to early 1900's scanned. The newer ones are probably only in print.

Pretty much what I have seen. The transactions of the American institute of Electrical Engineers is by far the most fascinating, a lot of the early stuff is free and fully scanned. Worth checking out of you already haven't.

 

[Sahib]

Not sure. Google and other resources have many old books from late 1800's to early 1900's scanned. The newer ones are probably only in print.

I obtained Indian edition of Hayt's 2013 and the relevant information is on a different page too.

 

[Sahib]

My hat off to you for doing some research. How refreshing. :thumbsup:

With more study you will find references for both. The trick is understanding how both positions/definitions are valid in their own right and how they both are physically possible.

You have two type systems that map to the same physical space so you can take either back out from that same physical space.

One issue, however, is by including 240/120V as two phase system in the family of poly phase systems, we deprive some of the advantages of having poly phase systems such as lower cost, longer life, lesser vibration etc., which rightfully belong to poly phase systems such as 'true' two phase motors and three phase motors.

 

[mivey]

One issue, however, is by including 240/120V as two phase system in the family of poly phase systems, we deprive some of the advantages of having poly phase systems such as lower cost, longer life, lesser vibration etc., which rightfully belong to poly phase systems such as 'true' two phase motors and three phase motors.

A system has its characteristics. We observe and make use of them as we can. We discover and utilize what already exists in the physical blueprint of nature.

Balanced two phase is different from quadrature two phase. It exists as part of a balanced polyphase system not by our design but because it already is by nature.

We can say different systems have different characteristics but a balanced two phase system is part of an ordered system whether we like it or not.

Quadrature two phase is not a balanced system but we don't kick it out of the polyphase group. It gets an asterick because it is really a subset of a four phase system which is a "true" balanced polyphase system.

Again, definitions matter. For a polyphase system using the canonical definition of phase system orders, balanced two phase is included and quadrature two phase is not. For systems that have the advantages you discussed it is the reverse.

However, balanced two phase has advantages that quadrature two phase does not. That does not change what they are but shows how we can use them.

You can define things however you want but it does not change nature. So pick the definition you like and be happy with it. Or be satisfied that each definition is valid in its own right. I promise the world will continue to spin its life cycle regardless of the choice you make so no worries.