Why is residential wiring known as single phase?

[mivey]

Wow, it appears you really do not read what I post.

I said a center tap has more in common with a delta connection than it does with a star.
Physically the connection of the windings in a star and a center tap is an Xeven connected to an Xodd, but a wye connection has an Xeven connected to an Xeven.

Yes there are other possible connections, but the OP asked about residential services. And in a true center-tap we do not have the individual center Xeven and Xodd terminals because they are actually the same point.

They are not the same point. Maybe on the outside of the can you only have three terminals for the smaller transformers but inside the cans, the transformers can be re-configured for parallel or series operation becuase there are four terminals inside. For the bigger transformers, four outside terminals are provided.

 

[rattus]

Jim, think about the wye for a moment. The phasors are drawn with the tails connected at a common point, the neutral. To obtain the L-L voltages, one subtracts one phasor from another.

Now think about the split phase system. How is this so different from the wye. Why not connect the phasors at the tail and subtract one from the other to obtain the L-L voltages as we do with a wye?

BTW, split phase apparently means that one phase is split into two??

 

[mivey]

BTW, split phase apparently means that one phase is split into two??

I think the use of "split phase" is more for motors although some have adopted it for the center-tapped transformer as well.

 

[Rick Christopherson]

And I have agreed that as phase shift AS YOU DEFINE IT TO BE WITH A TIME SHIFT is not there. But nobody cares except you because none of the transformer connections we use produce a time shift, but they do produce a phase shift USING THE PHASE SHIFT AS DEFINED BY A PHYSICAL DISPLACEMENT.

I don't understand where you can be coming up with this idea that a phase shift can exist without a time shift. That is exactly what a phase shift is! You shift the starting reference of one signal from another, and since our expressions for voltage are time-based, this is a time shift. (yes, in my previous posting I left the door open for your apparent phase shift that was actually an inversion.)

I am also quite perplexed about what you could possibly mean by a physical displacement as your phase shift. Sorry for the snarky comment, but does that mean you're going to move the wires some distance and call it a phase shift?

As it relates to the customary time-varying electrical expressions we use, please provide an example where a phase-shift is not a time shift. If the 180 degree shift is the only example you can come up with, that's because it is not a real phase-shift, as I have been saying. Do you have any situation that applies to this discussion where a phase shift is not a time shift?

 

[rattus]

I don't understand where you can be coming up with this idea that a phase shift can exist without a time shift. That is exactly what a phase shift is! You shift the starting reference of one signal from another, and since our expressions for voltage are time-based, this is a time shift. (yes, in my previous posting I left the door open for your apparent phase shift that was actually an inversion.)

I am also quite perplexed about what you could possibly mean by a physical displacement as your phase shift. Sorry for the snarky comment, but does that mean you're going to move the wires some distance and call it a phase shift?

As it relates to the customary time-varying electrical expressions we use, please provide an example where a phase-shift is not a time shift. If the 180 degree shift is the only example you can come up with, that's because it is not a real phase-shift, as I have been saying. Do you have any situation that applies to this discussion where a phase shift is not a time shift?

How does this pertain to the OP's question? Does he care?

 

[Rick Christopherson]

How does this pertain to the OP's question? Does he care?

It directly relates to it. If you spent as much time addressing the question as you did trying to dodge it, you would have seen that I already answered that.

 

[rattus]

It directly relates to it. If you spent as much time addressing the question as you did trying to dodge it, you would have seen that I already answered that.

How so? We have two phases, what does it matter if we call them real or apparent?

 

[Rick Christopherson]

How so? We have two phases, what does it matter if we call them real or apparent?

So when you get up in the morning, do you say there are two Rattus' in the bathroom because there is one standing before the bathroom mirror and one standing in the reflection? It matters, and you know it, and this is why you try to deflect from the actual question. It would be refreshing to be able to carry on a debate without your normal games of deception and deflection.

 

[rattus]

So when you get up in the morning, do you say there are two Rattus' in the bathroom because there is one standing before the bathroom mirror and one standing in the reflection? It matters, and you know it, and this is why you try to deflect from the actual question. It would be refreshing to be able to carry on a debate without your normal games of deception and deflection.

Just a civil answer Rick. That was another question.

 

[TimWA]

OP here. Yes the crazy person who innocently started this thread.

When I posted this question, an initial responder joked that I might consider just accepting the situation, in lieu of 600 replies.

We're now three times that. This thread must be stopped. I might be damaging the internet!

I hereby adjudicate that everyone's answer is slightly more correct than everyone else's.

 

[readydave8]

OP here. Yes the crazy person who innocently started this thread.

When I posted this question, an initial responder joked that I might consider just accepting the situation, in lieu of 600 replies.

We're now three times that. This thread must be stopped. I might be damaging the internet!

I hereby adjudicate that everyone's answer is slightly more correct than everyone else's.

The thread should not be stopped, it appears to be keeping some dangerous minds occupied and thus doing less damage to the real world.

 

[jim dungar]

If so, why the insistence that "the windings" are in phase when we really know that we are discussing the voltages in the windings?

I would have to go back and look but for the most part I have been concerned with the relationship of the winding terminals, such as X1 and X2, and simply shorten it to a general word 'winding'. I apologize if my use of the word winding was confusing to you. However, it seems most of the participants were abel to follow my word usage, and I am sure this is not what has caused this discussion to drag on.

Originally Posted by jim dungar

Any more blatant misrepresentation of what I have said or what I do recognize, will cause me to start acting like a moderator and not a participant.

Then practice what you preach first and stop getting upset when someone responds in kind:[/quote] Can you provide me with a quote where I positively stated a voltage was not real?
Although I think I may have questioned real sources of 'negative voltage' and 'negative current'.

http://forums.mikeholt.com/images/misc/quote_icon.png[/IMG] Originally Posted by jim dungar

You and Mivey, refuse to acknowledge that you are employing double negatives...

Originally Posted by jim dungar
Any other position, means Besoeker is wrong about paralleled connections or Mivey is wrong about his subscript usage or arrow assignment.

I am sure that back in 3rd or 4th grade I was taught:The combination of two numbers using a 'minus' sign resulting in an answer with a larger value must mean two negatives are involved, one in the operation and the other in the subtracted number.
I presented an analysis of your graphic, I combined information from your posts and Besoeker's, I then stated a conclusion. If I am misrepresenting something, then either of you should be refuting it, not obfuscating it.

 

[jim dungar]

How is this so different from the wye. Why not connect the phasors at the tail and subtract one from the other to obtain the L-L voltages as we do with a wye?

Why not follow the phasors associated with the individual winding terminals as they relate to the primary side?

The physical connections of a standard center tap or reconnectable transformer is different than the physical connections creating a wye.

 

[gar]

129304-0930 EST

Rick:

A resolver is a means of getting any desired phase shift from 0 to 360 by simply turning a knob. This phase shift will be mod 360.

Relative to the question of whether a phase shift is from a time delay or some other means, such as two mechanically linked alternators, it is not possible to know what is the source (a time delay line, two alternators, transformer secondaries, etc.) because a steady-state condition is assumed and this means you need to think mod X. Where mod X is in whatever set of units you use, for example 360 or 2*Pi, etc.

.

 

[gar]

120304-0942 EST

Yesterday in post 1716 Rattus provided a useful answer to the original post by TimWA.

There are very few reasons that a normal residential single phase center tapped secondary transformer would be used for anything other than single phase loads. However, practically it is desirable to describe the output as two phases, where the word phase is being used to label voltage sources that are different. You certainly don't want to connect leg A to leg B because these two voltages relative to neutral are 180 degrees out-of-phase. They are not in-phase.

If I wanted to directly charge a 110 V battery from via two diodes from my main panel without isolation, then I would most certainly be using the power company transformer secondary in a two phase full wave rectifier mode.

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[gar]

120304-0956 EST

rbalex:

It is my belief that the approach you used as a reason to claim that a center tapped secondary transformer has only single phase outputs is not not logically sound, because the the same argument can show that a normal 90 degree 2 phase system or a 120 degree 3 phase system are single phase.

You are equating that if "more than one mathematical function has the same argument", then the results of those functions are the same and thus should be classified singular. The word phase when used in describing a system is really a name for the voltage (or current or whatever) and not simply the argument of the function.

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[rattus]

120304-0942 EST

Yesterday in post 1716 Rattus provided a useful answer to the original post by TimWA.

There are very few reasons that a normal residential single phase center tapped secondary transformer would be used for anything other than single phase loads. However, practically it is desirable to describe the output as two phases, where the word phase is being used to label voltage sources that are different. You certainly don't want to connect leg A to leg B because these two voltages relative to neutral are 180 degrees out-of-phase. They are not in-phase.

If I wanted to directly charge a 110 V battery from via two diodes from my main panel without isolation, then I would most certainly be using the power company transformer secondary in a two phase full wave rectifier mode.

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Then the two voltages V1 and V2 exhibit two phases (measured in radians) not just one? And, the phases could be (wt) and (wt + PI), right? And, that makes two phases, right?

 

[gar]

120304-1026 EST

rattus:

Yes to your question.

What rbalex was doing was using a trig identity to change the sign in front of the function in order to make the argument of the function the same in two different functions.

Originally
f1 = A sin (wt), and
f2 = A sin (wt +180), and
then by a trig identity it was changed to
f2 = - A sin (wt). So now f1 and f2 are by rbalex's logic singular because the arguments are now the same. We are interested in the functions f1 and f2 and these are not the same.

It is all a matter of what dictionary one is using, and how those meanings represent what you are trying to study.

Because leg 1 and leg 2 are of opposing polarities (180 degrees out of phase) you can not connect them together. So even if all loads are single phase loads there are still two different source phases.

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[rattus]

120304-1026 EST

rattus:

Yes to your question.

What rbalex was doing was using a trig identity to change the sign in front of the function in order to make the argument of the function the same in two different functions.

Originally
f1 = A sin (wt), and
f2 = A sin (wt +180), and
then by a trig identity it was changed to
f2 = - A sin (wt). So now f1 and f2 are by rbalex's logic singular because the arguments are now the same. We are interested in the functions f1 and f2 and these are not the same.

It is all a matter of what dictionary one is using, and how those meanings represent what you are trying to study.

Because leg 1 and leg 2 are of opposing polarities (180 degrees out of phase) you can not connect them together. So even if all loads are single phase loads there are still two different source phases.

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I thought so.

 

[rbalex]

120304-1026 EST

rattus:

Yes to your question.

What rbalex was doing was using a trig identity to change the sign in front of the function in order to make the argument of the function the same in two different functions.

Originally
f1 = A sin (wt), and
f2 = A sin (wt +180), and
then by a trig identity it was changed to
f2 = - A sin (wt). So now f1 and f2 are by rbalex's logic singular because the arguments are now the same. We are interested in the functions f1 and f2 and these are not the same.

It is all a matter of what dictionary one is using, and how those meanings represent what you are trying to study.

Because leg 1 and leg 2 are of opposing polarities (180 degrees out of phase) you can not connect them together. So even if all loads are single phase loads there are still two different source phases.

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Looooong ago I explained to Bes why your misinterpretation of my position is in error. (It wasn't the time, he tried to introduce "hexiphase" into the discussion.) While the voltage functions of a conventional two-phase system may have the same t₀ and period, the functions don't have an identical phase.

Using a "conventional two-phase" system, and a common t₀ and period, you still will not be able to resolve the arguments to less than ([ωt + φ₀]) and ([ωt + φ₀]+ 90?) or their equivalent inverses. Likewise for conventional three-phase delta systems with a common t₀ and period, the arguments cannot be resolved to less than ([ωt + φ₀]), ([ωt + φ₀]+ 120?) and ([ωt + φ₀]+ 240?) or their equivalent inverses. However you don't introduce EVERY equivalent inverse into the argument mix to create new mythical phases which is what the "'2-phases' in a single-phase system" advocates are attermpting to do.

My earlier response to you was limited to the logical application of the definition of phase to a conventional 120/240V system where all valid voltage functions have the same t_0. That is, the arguments of every valid function can be reduced to ([ωt + φ₀]) OR its equivalent inverse -([ωt + φ₀]+180?), but you DON'T get to write them indiscriminatey in terms of BOTH - THAT is what introduces the myth.