Why is residential wiring known as single phase?

[rattus]

Why for?

Why for?

I really don't understand why Jim insists upon discussing transformer connections. I don't worry about it because my service comes from a pole mounted transformer and I am too old to climb the pole. Don't have any hooks anyway--never did for that matter, but my Uncle Joe did. Does that count?

The argument seems to center on the phrase "the sum of two in phase voltages in series", but one could just as easily say "the difference between two out of phase voltages referenced to neutral."

The fact that I choose neutral as a reference does not change a thing on the pole. I can't see any mathematical trick either, just an acceptable practice.

IMHO, we should not be having this discussion.

 

[rbalex]

Of course the periods are the same...

Thanks for stating the obvious; however, Bes has studiously, howbeit honestly, avoided acknowledging it.

 

[Besoeker]

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.

They were two current traces.
I_a and I_b.
They are not in phase.

 

[rbalex]

They were two current traces.
I_a and I_b.
They are not in phase.

Do they have the same period?

 

[Besoeker]

Do they have the same period?

As presented, I_a and I_b have the same conduction angles and the same fundamental frequency. And different starting points which means that they are not in phase.
Now, instead of asking questions, why not provide a simple answer.
I_a and I_b are clearly not in phase.
What does that tell you about the driving voltages?

 

[rattus]

Do they have the same period?

Why does it matter? I think even Jim Dungar will admit Va and Vb are out of phase but he wouldn't do it that way because it is a mathematical trick.

This thread has gone on and on because:

Some try to avoid admitting they are wrong by asking more and more questions and misusing mathematics.

Some get us embroiled in technical arguments not germane to the problem.

Some simply snipe by interjecting nonsense.

Time to give it up Bob.

 

[jim dungar]

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

Rotating the generator shaft 180?, rewinding a coil in the opposite direction, or simply swapping the output terminal designations, or swapping the output connections? Different physical actions yield different results.

 

[Besoeker]

Rotating the generator shaft 180?, rewinding a coil in the opposite direction, or simply swapping the output terminal designations, or swapping the output connections? Different physical actions yield different results.

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

 

[mivey]

Rotating the generator shaft 180?, rewinding a coil in the opposite direction, or simply swapping the output terminal designations, or swapping the output connections? Different physical actions yield different results.

Well gee whiz Jim, if I can take the two 180? displaced output voltages from a 180? rotated generator set and bolt those directly to the series additive 0? displaced voltage outputs from the single-phase transformer, doesn't that kind of clue you in that both voltages were physically there all along? It should be obvious if you would just stop and look for a minute.

 

[rbalex]

As presented, I_a and I_b have the same conduction angles and the same fundamental frequency. And different starting points which means that they are not in phase.
Now, instead of asking questions, why not provide a simple answer.
I_a and I_b are clearly not in phase.
What does that tell you about the driving voltages?

How do they have different starting points? Your diagram clearly indicates their periods both start at 0?. They must - since the periods for their respective driving voltages do also.

I have said they have the same phase and are not synchronized; you say they "...are clearly not in phase." I don?t know if they are or not since, within our discussion, phase and synchronism have been the only defined terms; so far, "in phase" is only a colloquialism.

I will be gone for about 4 hours.

 

[Rick Christopherson]

Why does it matter? I think even Jim Dungar will admit Va and Vb are out of phase but he wouldn't do it that way because it is a mathematical trick.

This thread has gone on and on because:

Some try to avoid admitting they are wrong by asking more and more questions and misusing mathematics.

Some get us embroiled in technical arguments not germane to the problem.

Some simply snipe by interjecting nonsense.

Time to give it up Bob.

 

[jim dungar]

I really don't understand why Jim insists upon discussing transformer connections.

Probably because they are important.

 

[jim dungar]

Well gee whiz Jim, if I can take the two 180? displaced output voltages from a 180? rotated generator set and bolt those directly to the series additive 0? displaced voltage outputs from the single-phase transformer, doesn't that kind of clue you in that both voltages were physically there all along? It should be obvious if you would just stop and look for a minute.

Where have i ever said you cannot connect out-of-phase voltages?
Where have I ever said that certain voltages do not exist.

Please take note of the math formulas you are using. You start with V12+V34=V14.
Then using a neutral reference point you say the formual to really use is V12-V43=V14 because V34=-V43.

Now physically reconnect the transformer by swapping the X3-X4 winding.
The starting formula now becomes V12+V43=V13.
Again if V34 = -V43, then -V34= V43, so now V12-V34=V13.

In both cases I mathematically swapped V34 with V43 and got identical answers, but the two actual physical connections provide different results. So does it matter if we say the source is -V43 when it is really V34.

I know that an AC waveform has a portion above the 0V point, which we often refer to as the positive half cycle, as well as a portion below, which we call negative. However when performing circuit analysis we look at a 'snapshot in time' RMS value when assigning a direction, and not the individual portions of the AC waveform(s).

 

[rattus]

Probably because they are important.

Why are they important to the OP's question?

Is it because you think we are claiming a two phase system? No one is.

 

[jim dungar]

Why are they important to the OP's question?

Because the OP specifically mentioned transformers in posts #1, #8, and #29.

Is it because you think we are claiming a two phase system? No one is.

Have not claimed you were doing so.
Cannot remember if I ever did have that misunderstanding, but I don't think so.

I have repeatedly said the basic positions are:
One group says: single phase systems are made up of (2) out-of-phase voltages connected in series.
One group says: single phase systems are made up of (2) in-phase voltages connected in series.

 

[Besoeker]

How do they have different starting points? Your diagram clearly indicates their periods both start at 0?.

My diagram very clearly indicates that their conduction periods do not start at the same point.

I_a starts at π/4. I_b starts at 5π/4.
Neither is at 0?.

Surely, as a professional engineer, you can understand that.

 

[Besoeker]

Where have i ever said you cannot connect out-of-phase voltages?

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

 

[rattus]

Because the OP specifically mentioned transformers in posts #1, #8, and #29.



Have not claimed you were doing so.
Cannot remember if I ever did have that misunderstanding, but I don't think so.

I have repeatedly said the basic positions are:
One group says: single phase systems are made up of (2) out-of-phase voltages connected in series.
One group says: single phase systems are made up of (2) in-phase voltages connected in series.

And one group claims that the split phase system (single phase) comprises two out of phase voltages defined relative to the neutral.

The first two statements are incomplete because they don't mention the neutral.

 

[rattus]

Post Script:

Post Script:

Jim, I have a little trouble describing the connection as series. For the two sources to be in series there would only two wires at their junction, but they are joined at the neutral as well. Perhaps a bit nit picking, but that is the way I think of it.

 

[jim dungar]

The first two statements are incomplete because they don't mention the neutral.

Haven't I been including a neutral when I write: Van+Vnb=Van-Vbn, where Vbn=-Vnb?


So then, including a neutral.
One group says: single phase systems are made up of (2) out-of-phase voltages connected in series with a neutral point.
One group says: single phase systems are made up of (2) in-phase voltages connected in series with a neutral point.

Or supply your own summations.