Why is residential wiring known as single phase?

[jim dungar]

With all due respect, why are we discussing polyphase?

I am not. I said the wiring of a single phase (two secondary windings) transformer ahd more in common with the wiring and analyis of a delta transformer than it did with a wye connection. Simply reinforcing the point that identification and interconnection of windings is more important than being simply manipulate math.

 

[jim dungar]

No, it is endless talk about the real world, stuff we already know.

Like Vbn = -Vnb, like Van+Vnb=Van-Vbn?

We wouldn't have a split phase system if the transformers were not connected correctly.

This is the heart of the discussion.

The real answer is "because there is only one transformer". Any reasonable person would assume it is properly connected.

The answer is: because of the way the single transformer is connected.
We know that V12 is in phase with V34 or else we would not be able to parallel them as 'any reasonable person knows'.
Connecting them V12+V34 is the actual physical connection of the transformer, which is a series connection of (2) in-phase voltages.

You have pointed out how markings on transformers are used to ensure that physical connections are made correctly and how they can be useful in mathematical formulas for establishing 'base' relationships. My point of mentioning delta and wye connections was to affirm the importance of transformer 'dots' in creating real world connections (a simple misarrangement of dots can create an open-delta instead of an open-wye).

You can play with your mathematical inversions all you like, but as soon as you physically rotate a winding by 180?, you will get a different real world result. If you do not physically rotate the winding aren't you just manipulating it mathematically?

 

[K8MHZ]

Coming up on post #1400.

Sometime in the future when we all have been shuffled off this mortal coil, minstrels will sing of this thread.

 

[Besoeker]

HUH??? What does "timing" have to do with period? Your own diagram shows the period is from 0 to 360?

It also shows that I_a and I_b are not in phase.
Thus, the voltages driving them are not in phase.

 

[rbalex]

It also shows that I_a and I_b are not in phase.
Thus, the voltages driving them are not in phase.

Does that mean you don't agree that the time while either I_a or I_b are zero because they are clipped or rectified is still part of the period of their fundamental harmonic?.

 

[gar]

120425-1623 EST

jim dungar:

Now that you have connected X2 to X3 make the parallel connection by connecting X1 to X4 and there will be fireworks because X1 and X4 are not in-phase. This is obviously an undesirable parallel connection, but it is a parallel connection.

.

 

[jim dungar]

Now that you have connected X2 to X3 make the parallel connection by connecting X1 to X4 and there will be fireworks because X1 and X4 are not in-phase. This is obviously an undesirable parallel connection, but it is a parallel connection.

So now are we dealing with the phasing of individual terminals?

 

[mivey]

Who, other than you has made claims of non-existent voltages?

You, in part of your double-speak. You say the voltages at the windings MUST be in phase and anything else is a math trick. We all agree that V12 is in phase with V34. Then you agree that V43 is not in phase with V12. If V43 is not in phase with V12 then, by double-speak, V43 is not a real voltage because only in-phase voltages exist at the transformer output. It appears you try to have your cake and eat it too.

You did notice that the combined wiring diagram does have physical connections that are not the same as in the two individual ones don't you?

And none of it changes the winding voltages that exist before or after the connections.

Open delta 5 is connected to 4, open wye 5 is connected to 1, combined 5 is connected to 3, 7, and 2.

5 is not connected to 3,7,2. The dashed line was to represent the missing 120? voltage. I'll replace it with a labeled arrow to avoid any confusion.

Try your example again without physically reconnecting the transformers.

Why don't we just look at the transformer as-is for a starting point. The voltage across 1-2-3-4 is from the standard, single-phase transformer we have all been discussing. We would all agree that V12 is in phase with V34 in this transformer. But as the usage indicates, V12 is phase-opposed to V43. It is not a math trick but a physical reality. The use of the phase-opposed voltage allows us to produce the missing 120? voltage.

Try the V34 = -V43 argument by connecting a transformer with the windings actual reversed from each other.

Why don't we address what I presented first before moving on?

 

[mivey]

With all due respect, why are we discussing polyphase?

If we discuss phase differences, it is only natural to include examples from familiar systems with phase differences.

 

[jim dungar]

Now that you have connected X2 to X3 make the parallel connection by connecting X1 to X4 and there will be fireworks because X1 and X4 are not in-phase.

Take any two terminals that define a voltage between them, directly connect them together and you will more than likely get fireworks.:slaphead:
Even if it is X1 connected to X2 or X3 connected to X4

This is obviously an undesirable parallel connection, but it is a parallel connection.

Confirming my position that, when dealing with transformers, the actual connections are the issue; all parallel winding connections are not equal nor are all series ones.
Connecting X2+X3 and X1+X4 is an entirely different arrangement than X1+X3 and X2+X4.

A 180? rotation, inversion, or swap of voltage relationships in mathematical formulas is not the same as actually rotating, swapping, inverting real connections.

 

[mivey]

If a voltage source has two wires, then it is a single phase source. If a load has only two wires, then it is a single phase load. Extending this I believe you should conclude that a system with more than two source wires has the possibility of being a source of more than one phase.

You would think that would be a such a simple understanding. In fact, I have seen that written almost word for word like you have it here in one of the reference texts I have somewhere.

 

[mivey]

If you do not physically rotate the winding aren't you just manipulating it mathematically?

The 1-2-3-4 winding in my example has the "V12 in phase with V34" voltages as well as the "V12 phase-opposed to V43" voltages. You do not have to physically rotate the transformer connections for these voltages to exist as they are already there waiting to be used.

V12 is in series with V34. V21 is in series with V65. We do not have to re-connect the transformer for both to be true at the same time.

 

[jim dungar]

You, in part of your double-speak. You say the voltages at the windings MUST be in phase and anything else is a math trick. We all agree that V12 is in phase with V34. Then you agree that V43 is not in phase with V12. If V43 is not in phase with V12 then, by double-speak, V43 is not a real voltage because only in-phase voltages exist at the transformer output. It appears you try to have your cake and eat it too.

It is really too bad that you cannot follow a logical argument that differs from your opinion.
I know I have said this many times in the past but you must have missed it.
V43=-V34

A mathematical operation is not the same as a physical operation.

X1->X2+X3->X4 is the industry standard physical connection, and to my knowledge it is not disputed by anyone. I know that I refer this as (2) in-phase voltages connected in series.
X1->X2+X4->X3 is an entirely different physical connection. It is pretty hard to recall everything, but I am pretty sure I have mentioned this as (2) out-of-phase voltages connected in series. I know I posted a graphic of this specific connection.

Connection 1 = V12+V34=V14
Connection 2 = V12+V43+V13

Oh yeah in case you are not following:
Connection 1 manipulated by math = V12-V43=V14

 

[mivey]

Take any two terminals that define a voltage between them, directly connect them together and you will more than likely get fireworks.:slaphead:
Even if it is X1 connected to X2 or X3 connected to X4

I have seen it noted many times in different reference texts that the voltages at the ends of a winding are 180? out of phase with each other. But the reader certainly should understand the context of the use and I think we all do.

Connecting X2+X3 and X1+X4 is an entirely different arrangement than X1+X3 and X2+X4.

Has anyone disputed that?

A 180? rotation, inversion, or swap of voltage relationships in mathematical formulas is not the same as actually rotating, swapping, inverting real connections.

Do you not agree that rotating a generator winding 180? is the same as the 180? mathematical rotation?

If a mathematical rotation models a transformer rotation, and results in a real physical degree difference when applied in the real world, does that not tell us the mathematical degree change is simply a model of a real physical degree change?

 

[mivey]

It is really too bad that you cannot follow a logical argument that differs from your opinion.

Right back at you.

A mathematical operation is not the same as a physical operation.

The mathematical operations that show
V12 = V@0? =-V21
and
V21 = V@180? = -V12

are used in the physical transformer example I provided. In other words, V12 = V@0? has a mathematical AS WELL AS A PHYSICAL phase difference from V21 = V@180?. When the winding output is used as V@0? we see the results we all know and love as in-phase voltages in the single-phase transformer. When the winding output is used as V@180? we see the physical results that show it is more than just math but a physical reality. Why is that so hard for you to see?

X1->X2+X3->X4 is the industry standard physical connection, and to my knowledge it is not disputed by anyone. I know that I refer this as (2) in-phase voltages connected in series.

Understood.

X1->X2+X4->X3 is an entirely different physical connection. It is pretty hard to recall everything, but I am pretty sure I have mentioned this as (2) out-of-phase voltages connected in series. I know I posted a graphic of this specific connection.

I have not shown that connection in my example. I have shown that both X1->X2+X3->X4 and X2->X1+X6->X5 are present. Read it again: both X1->X2 and X2->X1 are there as the transformer is connected. I'm not re-connecting anything from series to parallel and back again.

Connection 1 = V12+V34=V14
Connection 2 = V12+V43=V13

OK. But V12+V43=V13 is not what I have connected so what is your point?

 

[gar]

120225-1930 EDT

jim:

Relative to your post 1387. Not really individual terminals, but I saw no need to define the quite obvious reference point of the X2-X3 connection.

I said this before, but to repeat.

Can you take two voltage sources of equal voltage magnitude, frequency, and in-phase, and connect them in parallel with no appreciable circulating current? This is essentially what you have to do to parallel generators.

Now reverse the phase (180 deg shift, or inversion, or whatever other name suits you) of one of the voltage sources. Now can you parallel these sources without a lot of circulating current? When X2 is connected to X3 and upon the connection of X1 to X4 there is a large current, then you have this condition.

.

 

[Besoeker]

Does that mean you don't agree that the time while either I_a or I_b are zero because they are clipped or rectified is still part of the period of their fundamental harmonic?.

It means that I_a and I_b are not in phase.

 

[Besoeker]

It is really too bad that you cannot follow a logical argument that differs from your opinion.

In the circuit in post #1004, are I_a and I_b in phase?
That's just yes or no.

 

[rbalex]

It means that I_a and I_b are not in phase.

It means in 1004 you don't recognize you have effectively superimposed two voltage traces and you don't recognize you have two currents, I_a and I_b, with the same period P as their respective driving voltages.

 

[rattus]

Why?

Why?

It means in 1004 you don't recognize you have effectively superimposed two voltage traces and you don't recognize you have two currents, I_a and I_b, with the same period P as their respective driving voltages.

Of course the periods are the same, but what does that prove? We have two sinusoids with phases

(wt +phi0) and (wt +phi0 +PI)

The difference in phase is PI. They cannot be in phase. That's all folks!

So why are we still discussing this obvious point?