I'm posting this to try to settle an argument going on in another
newsgroup (alt.home.repair) about phases in electrical power.

Over there, someone posted a question about GFCI breakers that morphed
into a discussion of multiphase electrical power. A disagreement arose
thereafter about whether a center-tapped transformer actually delivers
two separate phases of electricity or not. I'd like to get opinions
here, since at least some folks here have engineering backgrounds: over
there (a.h.r.), not so much. People there tend to be more electrician
types, rather than EEs and such.

The discussion started with a mention of 2-phase power. Turns out that
in the world of electrical power, this has a specific meaning. It refers
to a now-obsolete system of generating power in 2 phases that were 90°
apart, and was used at Niagara Falls:

http://www.3phasepower.org/2phasesystems.htm

And of course there's 3-phase power, widely used today.

The problem is this: several people, myself included, contend that the
two "legs" of power produced by a center-tapped transformer do, in fact,
constitute two separate phases of power, 180° apart. (This is how
household power is delivered in North America, with a step-down xfmr at
the power pole delivering 240 volts in the form of 120-0-120.)

Now it's true that in the electrical industry, this is called
"split-phase" power, and if you tried to tell the guy behind the counter
at the electrical supply house that it's 2-phase, he'd look at you funny.

However, I (and others) say that this is, in fact, true 2-phase power,
even if it's not called that. It just happens to be trivially easy to
generate it from a single phase, as it only involves inversion. (Unlike
3-phase, which requires rotary converters or electronic devices to
generate from single-phase power.)

Take, for example, any push-pull amplifier with a phase inverter or
phase splitter in front of it: it generates two separate phases out of a
single phase.

So, what do y'all say?


--
Comment on quaint Usenet customs, from Usenet:

To me, the *plonk...* reminds me of the old man at the public hearing
who stands to make his point, then removes his hearing aid as a sign
that he is not going to hear any rebuttals.

"David Nebenzahl"

I'm posting this to try to settle an argument going on in another
newsgroup (alt.home.repair) about phases in electrical power.

Over there, someone posted a question about GFCI breakers that morphed
into a discussion of multiphase electrical power. A disagreement arose
thereafter about whether a center-tapped transformer actually delivers two
separate phases of electricity or not. I'd like to get opinions here,
since at least some folks here have engineering backgrounds: over there
(a.h.r.), not so much. People there tend to be more electrician types,
rather than EEs and such.

The discussion started with a mention of 2-phase power. Turns out that in
the world of electrical power, this has a specific meaning. It refers to a
now-obsolete system of generating power in 2 phases that were 90° apart,
and was used at Niagara Falls:

http://www.3phasepower.org/2phasesystems.htm

And of course there's 3-phase power, widely used today.

The problem is this: several people, myself included, contend that the two
"legs" of power produced by a center-tapped transformer do, in fact,
constitute two separate phases of power, 180° apart. (This is how
household power is delivered in North America, with a step-down xfmr at
the power pole delivering 240 volts in the form of 120-0-120.)

Now it's true that in the electrical industry, this is called
"split-phase" power, and if you tried to tell the guy behind the counter
at the electrical supply house that it's 2-phase, he'd look at you funny.

However, I (and others) say that this is, in fact, true 2-phase power,
even if it's not called that. It just happens to be trivially easy to
generate it from a single phase, as it only involves inversion. (Unlike
3-phase, which requires rotary converters or electronic devices to
generate from single-phase power.)

Take, for example, any push-pull amplifier with a phase inverter or phase
splitter in front of it: it generates two separate phases out of a single
phase.

So, what do y'all say?


** It's clearly two phase power, no doubt about that.

There are two AC waves that differ only in phase and if both "phases" are
loaded equally, the neutral current is zero.

So it is completely analogous to three phase power.

The 90 degree system is just an obsolete odd ball only a moronic pedant
would even mention.



..... Phil

David Nebenzahl wrote:
I'm posting this to try to settle an argument going on in another
newsgroup (alt.home.repair) about phases in electrical power.

Over there, someone posted a question about GFCI breakers that morphed
into a discussion of multiphase electrical power. A disagreement arose
thereafter about whether a center-tapped transformer actually delivers
two separate phases of electricity or not. I'd like to get opinions
here, since at least some folks here have engineering backgrounds: over
there (a.h.r.), not so much. People there tend to be more electrician
types, rather than EEs and such.

The discussion started with a mention of 2-phase power. Turns out that
in the world of electrical power, this has a specific meaning. It refers
to a now-obsolete system of generating power in 2 phases that were 90°
apart, and was used at Niagara Falls:

http://www.3phasepower.org/2phasesystems.htm

And of course there's 3-phase power, widely used today.

The problem is this: several people, myself included, contend that the
two "legs" of power produced by a center-tapped transformer do, in fact,
constitute two separate phases of power, 180° apart. (This is how
household power is delivered in North America, with a step-down xfmr at
the power pole delivering 240 volts in the form of 120-0-120.)

Now it's true that in the electrical industry, this is called
"split-phase" power, and if you tried to tell the guy behind the counter
at the electrical supply house that it's 2-phase, he'd look at you funny.

However, I (and others) say that this is, in fact, true 2-phase power,
even if it's not called that. It just happens to be trivially easy to
generate it from a single phase, as it only involves inversion. (Unlike
3-phase, which requires rotary converters or electronic devices to
generate from single-phase power.)

Take, for example, any push-pull amplifier with a phase inverter or
phase splitter in front of it: it generates two separate phases out of a
single phase.

So, what do y'all say?


I do industrial EE work and terminology can really
get screwed up at times.

You have a CT (center Tap) this gives you 2 phases, using the
CT as the common, which of course are 180 degrees apart. How ever,
if you need 230 volts, you would need to use the 2 outer legs which
will only give you a single phase for that circuit. Hence, only
one winding over all. CT means nothing here.

To qualify for a phase, it must has a common or an opposing leg.

Lets look at a floating Delta 3 phase system, even though it has
no common to qualify it as 3 circuits 120 degree's out of phase, it
does have 3 separate windings, each 120 degree's out and can supply
a circuit on each winding if it wished.

Looking at a STAR (WYE), one end of each phase (winding) is connected
to a common point.. This common point does not need to be used but is in
some cases.

The point is, there are 3 individual windings that are out of phase
with each other. Makes it 3 phase...

In the case of residential, the CT will give you 2 phases of 180
degree's when you only need 115 volt circuits how ever, because the
transformer here is really only a single winding with a CT, when you
need full voltage for 230 appliances, that circuit ends up being
a single phase.. How ever, most appliances like that also have the
CT/Neutrual so it can use half of that to operate the control electronics.

Some people call it split phase, only because you are taking a single
phase and splitting it in the middle. But that does give you a 2 phase
source if you to use the CT as the common for both.. It would be the
same as 2 transformers with their secondaries joined on one side only to
form a CT.

Remember "Split Phase" only means a single winding with a CT it,
hence, you have split the phase in half!

Now here's a tricky one.. Just think of the 3 phase system with a CT
in each winding. Now we're talking !

Jamie

If there were two electrically isolated windings, with opposite polarity,
you would clearly have two phases. (I think.)

But the center tap gives them a common neutral. So are they still separate
phases? I'm inclined to say yes, because in a conventional three-phase
system, loads can be attached to individual phases, or across two phases for
a higher voltage. And these are considered multi-phase systems.

On Fri, 21 Jan 2011 18:09:26 -0800, David Nebenzahl
wrote:

The discussion started with a mention of 2-phase power. Turns out that
in the world of electrical power, this has a specific meaning. It refers
to a now-obsolete system of generating power in 2 phases that were 90°
apart, and was used at Niagara Falls:

http://www.3phasepower.org/2phasesystems.htm

And of course there's 3-phase power, widely used today.

The problem is this: several people, myself included, contend that the
two "legs" of power produced by a center-tapped transformer do, in fact,
constitute two separate phases of power, 180° apart. (This is how
household power is delivered in North America, with a step-down xfmr at
the power pole delivering 240 volts in the form of 120-0-120.)


Well, if you want to be correct, the house power is split phase, and
not two phase. I suppose there is an arguement that it is two phase,
but say that to a power engineer and you'll get the old raised
eyebrows response!

On 1/22/2011 7:27 AM, PeterD wrote:
Well, if you want to be correct, the house power is split phase, and
not two phase. I suppose there is an arguement that it is two phase,
but say that to a power engineer and you'll get the old raised
eyebrows response!

Ding! We have a winner.

Thank you peter.

Jeff

In article ,
"William Sommerwerck" wrote:

If there were two electrically isolated windings, with opposite polarity,
you would clearly have two phases. (I think.)

Reminds me of the story of two carpenters. One says, "Half of my nails
have the head on the wrong end." His partner responds, "You dummy,
those are for the other side of the house!"

On Sat, 22 Jan 2011 14:24:13 -0500, Fred McKenzie
wrote:

In article ,
"William Sommerwerck" wrote:

If there were two electrically isolated windings, with opposite polarity,
you would clearly have two phases. (I think.)

Reminds me of the story of two carpenters. One says, "Half of my nails
have the head on the wrong end." His partner responds, "You dummy,
those are for the other side of the house!"

And the other carpenters doing the other side of the house: "Damn, I
just cut this board too short." His partner replies, "Simple, just
turn it around and cut somemore off the other end..."

On 1/22/2011 5:27 AM PeterD spake thus:

On Fri, 21 Jan 2011 18:09:26 -0800, David Nebenzahl
wrote:

The discussion started with a mention of 2-phase power. Turns out
that in the world of electrical power, this has a specific meaning.
It refers to a now-obsolete system of generating power in 2 phases
that were 90° apart, and was used at Niagara Falls:

http://www.3phasepower.org/2phasesystems.htm

And of course there's 3-phase power, widely used today.

The problem is this: several people, myself included, contend that
the two "legs" of power produced by a center-tapped transformer do,
in fact, constitute two separate phases of power, 180° apart. (This
is how household power is delivered in North America, with a
step-down xfmr at the power pole delivering 240 volts in the form
of 120-0-120.)

Well, if you want to be correct, the house power is split phase, and
not two phase. I suppose there is an arguement that it is two phase,
but say that to a power engineer and you'll get the old raised
eyebrows response!

Welllll ... that's pretty much what I wrote. So I take it you agree with
me that it is, in fact, 2-phase power, correct?


--
Comment on quaint Usenet customs, from Usenet:

To me, the *plonk...* reminds me of the old man at the public hearing
who stands to make his point, then removes his hearing aid as a sign
that he is not going to hear any rebuttals.

On 1/22/2011 6:37 PM, David Nebenzahl wrote:
On 1/22/2011 5:27 AM PeterD spake thus:

On Fri, 21 Jan 2011 18:09:26 -0800, David Nebenzahl
wrote:

The discussion started with a mention of 2-phase power. Turns out
that in the world of electrical power, this has a specific meaning.
It refers to a now-obsolete system of generating power in 2 phases
that were 90° apart, and was used at Niagara Falls:

http://www.3phasepower.org/2phasesystems.htm

And of course there's 3-phase power, widely used today.

The problem is this: several people, myself included, contend that
the two "legs" of power produced by a center-tapped transformer do,
in fact, constitute two separate phases of power, 180° apart. (This
is how household power is delivered in North America, with a
step-down xfmr at the power pole delivering 240 volts in the form
of 120-0-120.)

Well, if you want to be correct, the house power is split phase, and
not two phase. I suppose there is an arguement that it is two phase,
but say that to a power engineer and you'll get the old raised
eyebrows response!

Welllll ... that's pretty much what I wrote. So I take it you agree with
me that it is, in fact, 2-phase power, correct?


In a word, no.

Power distribution being what it is, the 240/120 transformer on the
pole is sourced with _ONE_ phase of the 3-phase feed for the area.
That there is a center tap allowing for 120/120 or 240 loads is
immaterial. It's STILL single phase.

Jeff

"Jeffrey Angus"


Welllll ... that's pretty much what I wrote. So I take it you agree with
me that it is, in fact, 2-phase power, correct?


In a word, no.

Power distribution being what it is, the 240/120 transformer on the
pole is sourced with _ONE_ phase of the 3-phase feed for the area.

** Totally irrelevant how the 2-phase is derived.


That there is a center tap allowing for 120/120 or 240 loads is
immaterial. It's STILL single phase.

** Pedantic nonsense.

There are two AC waves that differ only in phase and if both "phases" are
loaded equally, the neutral current is zero.

So it is completely analogous to 3-phase power.

The 90 degree system is just an obsolete odd ball only a moronic pedant
would even mention.




..... Phil

On 1/22/2011 4:49 PM Phil Allison spake thus:

"Jeffrey Angus"

Welllll ... that's pretty much what I wrote. So I take it you
agree with me that it is, in fact, 2-phase power, correct?

In a word, no.

Power distribution being what it is, the 240/120 transformer on the
pole is sourced with _ONE_ phase of the 3-phase feed for the
area.

** Totally irrelevant how the 2-phase is derived.

That there is a center tap allowing for 120/120 or 240 loads is
immaterial. It's STILL single phase.

** Pedantic nonsense.

There are two AC waves that differ only in phase and if both "phases" are
loaded equally, the neutral current is zero.

So it is completely analogous to 3-phase power.

The 90 degree system is just an obsolete odd ball only a moronic pedant
would even mention.

I have to say I totally agree with Phil here. Especially the reference
to "true" 2-phase power brought up in this argument (the one over on
a.h.r), meaning that totally antiquated and obsolete system.

Those with which I disagree seem to think that just because the two
phases aren't somehow manufactured separately, by two different windings
of a generator or some such, that the center-tapped xfmr can't possibly
supply two separate phases, when it so clearly does just that.


--
Comment on quaint Usenet customs, from Usenet:

To me, the *plonk...* reminds me of the old man at the public hearing
who stands to make his point, then removes his hearing aid as a sign
that he is not going to hear any rebuttals.

On 1/22/2011 4:45 PM Jeffrey Angus spake thus:

Power distribution being what it is, the 240/120 transformer on the
pole is sourced with _ONE_ phase of the 3-phase feed for the area.
That there is a center tap allowing for 120/120 or 240 loads is
immaterial. It's STILL single phase.

Keep in mind the premise of my original question. Remember I pointed out
that 120-0-120 current supplied by a center-tapped transformer is *not*
called "2-phase" by those in the electrical power industry, but that it
is, in fact, 2-phase power. Do you disagree that there are actually two
separate phases of power present at the secondary of the transformer?

Regardless of what they call it ...


--
Comment on quaint Usenet customs, from Usenet:

To me, the *plonk...* reminds me of the old man at the public hearing
who stands to make his point, then removes his hearing aid as a sign
that he is not going to hear any rebuttals.

On 1/22/2011 7:07 PM, David Nebenzahl wrote:
On 1/22/2011 4:45 PM Jeffrey Angus spake thus:

Power distribution being what it is, the 240/120 transformer on the
pole is sourced with _ONE_ phase of the 3-phase feed for the area.
That there is a center tap allowing for 120/120 or 240 loads is
immaterial. It's STILL single phase.

Keep in mind the premise of my original question. Remember I pointed out
that 120-0-120 current supplied by a center-tapped transformer is *not*
called "2-phase" by those in the electrical power industry, but that it
is, in fact, 2-phase power. Do you disagree that there are actually two
separate phases of power present at the secondary of the transformer?

Regardless of what they call it ...



Nope, single phase.

The definition of "more than one" phase is a difference
of something other than 0 or 180 degrees.

With either 2-Phase (the old 90 degree system) or 3-phase
(current 120 degree system) the phases can NOT be generated
with a simple transformer. They are generated by multiple
alternators mounted on a common shaft.

With a single transformer, and a center tap, you have two
voltages, in phase, that add together.

It's single phase.

Jeff

Jeffrey Angus wrote:

On 1/22/2011 7:27 AM, PeterD wrote:

Well, if you want to be correct, the house power is split phase, and
not two phase. I suppose there is an arguement that it is two phase,
but say that to a power engineer and you'll get the old raised
eyebrows response!


Ding! We have a winner.

Thank you peter.

Jeff

having a CT in a winding gives you 2 phases, 180 apart..

Calling it split phase is just a method of doing it.

Lets look at it this way..

Take a control xfomer..

If I was to wire the secondary as

X1, X2+X3, X4;

X2 and X3 being the CT, I now have a source that has 2 secondaries
(2 windings) that can give me 180 degree shift via the CT. This gives
me 2 phases..Why? because they are not in phase with each other.. It
does not matter if they are only 1 degree off from each other.. They
would be two difference phases, because we are using the CT as the
common point. Same as, if you were to use the STAR Center of a WYE
transformer as the common point, this would give you 3 phases which
we all know are 120 degrees different from each one. The analogy isn't
any different if you had the pole pig which is just a single winding
with a CT in it on the secondary side for your common. Other wise known
as a split phase because can treat that as a single phase to get the
full voltage or split phase to get half voltage with 180 shifts.(2 phases)


Now, take that same xformer I have above there and....

X2, X1+X3, X4;

What do you get? You get two different power points sharing a CT but
in phase with each other. And yes, I've seen this done before to avoid
over voltage through grounds if the neutral was ever lifted for some
reason. This basically is only one phase and does not allow you to
use them for double voltage. In fact, you'll get no voltage between X2
and X4.


Oh well.

Jamie

Jeffrey Angus wrote:

On 1/22/2011 6:37 PM, David Nebenzahl wrote:

On 1/22/2011 5:27 AM PeterD spake thus:

On Fri, 21 Jan 2011 18:09:26 -0800, David Nebenzahl
wrote:

The discussion started with a mention of 2-phase power. Turns out
that in the world of electrical power, this has a specific meaning.
It refers to a now-obsolete system of generating power in 2 phases
that were 90° apart, and was used at Niagara Falls:

http://www.3phasepower.org/2phasesystems.htm

And of course there's 3-phase power, widely used today.

The problem is this: several people, myself included, contend that
the two "legs" of power produced by a center-tapped transformer do,
in fact, constitute two separate phases of power, 180° apart. (This
is how household power is delivered in North America, with a
step-down xfmr at the power pole delivering 240 volts in the form
of 120-0-120.)


Well, if you want to be correct, the house power is split phase, and
not two phase. I suppose there is an arguement that it is two phase,
but say that to a power engineer and you'll get the old raised
eyebrows response!


Welllll ... that's pretty much what I wrote. So I take it you agree with
me that it is, in fact, 2-phase power, correct?


In a word, no.

Power distribution being what it is, the 240/120 transformer on the
pole is sourced with _ONE_ phase of the 3-phase feed for the area.
That there is a center tap allowing for 120/120 or 240 loads is
immaterial. It's STILL single phase.

Jeff


Oh, so now that we have a CT as a neutral (common), how do you explain
the two different phase angles we now have ?

Last time I went to school, phase count was the number of
phase angles you have that are unique in degrees.

does not matter how you derived it..

If I plug in an inverter that operates from a single phase circuit
and it generates 3 phases that are 120 degree's apart, does that mean
it much be single phase because it started from a single phase source?


Jamie

On 1/22/2011 6:49 PM Jamie spake thus:

If I plug in an inverter that operates from a single phase circuit
and it generates 3 phases that are 120 degree's apart, does that mean
it much be single phase because it started from a single phase source?

Excellent question. I await answers.

So far, we have two objections to a center-tapped transformer giving two
phases, both very doubtful:

1. Not two phase because the "source" (i.e., the other side of the xfmr)
is single phase.

2. Not two phase because two phases that are 180° are not actually two
phases (?!?!?!).


--
Comment on quaint Usenet customs, from Usenet:

To me, the *plonk...* reminds me of the old man at the public hearing
who stands to make his point, then removes his hearing aid as a sign
that he is not going to hear any rebuttals.

"Jeffrey Angus"


Nope, single phase.

The definition of "more than one" phase is a difference
of something other than 0 or 180 degrees.


** Who's " definition " is that ????

I wonder ........



...... Phil

And of course there's 3-phase power, widely used today.

The problem is this: several people, myself included, contend that the
two "legs" of power produced by a center-tapped transformer do, in fact,
constitute two separate phases of power, 180° apart. (This is how
household power is delivered in North America, with a step-down xfmr at
the power pole delivering 240 volts in the form of 120-0-120.)


David et al

A specific that many are not aware of and are left wondering when
discussed is the following.

The transformer that feeds your home and many small businesses has a
single phase impressed across the primary winding. Usually called a HV
winding. No big deal for this discussion. The "secondary winding" is
actually two identical windings. Sometimes called tertiary windings.
But this term usually leaves most on the dark. Not a commonly used
term since we don't usually get into the actual electrical and/or
mechanical construction of transformers, let alone the ones feeding
our homes. To most they are simply an unknown on the pole in the alley
or in a pedestal box in the front yard of residential houses.

Back to the actual transformer. A primary winding and two identical
secondary windings. The seondary windings are wound identically within
and about the primary winding. Well insulated of course. The primary
winding impresses each winding identically, in this case, 120 volts.
So the operation of the secondary windings are identical.

The secondary windings are connected in an addtive fashion to give 240
volts across the ends of the connected windings. Their common
terminal, internally connected, is sometimes thought of as a "center"
tap. But the windings are not actually centertapped. They are only
connected in a additive fashion to give the desired 240 volts. 120
volts is of course is simply a connection to a hot lead and the
common terminal. When both windings are utilized we end up with two
"hot" leads which are used for the 120 volt loads. The same additive
principle could be used to give perhaps 360 or 480 volts.

But in no case, with the information presented here, is there any
method or device utilized to give any additional phases. One or two or
more. The hot legs are simply the same phase, transformed as needed,
added within the transformer, with the resultant two hot legs, 180
degrees out of phase with each other. Were the windings connected "in
phase" the available voltage would be 50% and the power, amps,
available doubled.

Three phase distribution starts with a generator with 3 sets of
windings that is distributed as three phase and utuilzed as needed.
Residential as this discussion continues, and large users with many
motor (inductive) loadings commonly found in motors 5 or more HP. The
5 HP figure is an industry norm that takes advantage of the inherent
advantages of 3 phase. Mainly distribution costs and three phase
motors.

Disclaimer: Transformers, power distribution, are not my usual area of
expertise. This would be several different lifelong careers followed
by others. I simply deal with it on an almost daily basis and have for
over 50 years.

Enough for a long day.

Bob AZ

"Bob AZ"

( snip tedious drivel)

But in no case, with the information presented here, is there any
method or device utilized to give any additional phases. One or two or
more. The hot legs are simply the same phase, transformed as needed,
added within the transformer, with the resultant two hot legs, 180
degrees out of phase with each other.


** A really beautiful example of "double think" if I ever saw one.


Three phase distribution starts with a generator with 3 sets of
windings that is distributed as three phase and utuilzed as needed.

** And if it had only 2 windings instead of 3 ??

Two AC waves would be produced simultaneously, remaining always 180 degrees
apart in phase and be completely * indistinguishable * from any other means
of creating the same situation.



...... Phil

On 1/23/2011 9:05 AM, Jamie wrote:
Jeffrey Angus wrote:
It's single phase.

Jeff
Big JOKE!

You fail.

I bow to your superior logic and wit.

Jeff

Jeffrey Angus wrote:

On 1/22/2011 7:07 PM, David Nebenzahl wrote:

On 1/22/2011 4:45 PM Jeffrey Angus spake thus:

Power distribution being what it is, the 240/120 transformer on the
pole is sourced with _ONE_ phase of the 3-phase feed for the area.
That there is a center tap allowing for 120/120 or 240 loads is
immaterial. It's STILL single phase.


Keep in mind the premise of my original question. Remember I pointed out
that 120-0-120 current supplied by a center-tapped transformer is *not*
called "2-phase" by those in the electrical power industry, but that it
is, in fact, 2-phase power. Do you disagree that there are actually two
separate phases of power present at the secondary of the transformer?

Regardless of what they call it ...



Nope, single phase.

The definition of "more than one" phase is a difference
of something other than 0 or 180 degrees.

With either 2-Phase (the old 90 degree system) or 3-phase
(current 120 degree system) the phases can NOT be generated
with a simple transformer. They are generated by multiple
alternators mounted on a common shaft.

With a single transformer, and a center tap, you have two
voltages, in phase, that add together.

It's single phase.

Jeff
Big JOKE!

You fail.

David Nebenzahl wrote:

A disagreement arose
thereafter about whether a center-tapped transformer actually delivers
two separate phases of electricity or not.

So, what do y'all say?

Formally, yes, there exist two phases set apart 180º. But formally also that
is never called a "two-phase system".

Reasons:
1.- In polyphase system there is an usual understanding that phases are
different when you can not get the other phase by simple means other than
using transformers (or transformer arrays). In a 3 Phase system, there is no
way to get a phase 120º away by adding, subtracting or switching cable ends
of one phase. In a true two phase system, be it a three wire part of a 3
phase system or the Niagara example, there is no way to get the other phase
(120º or 90º) by playing with the connections. In a "split phase" system,
the 180º phase is equal (in a balanced system) to the other one by just
exchanging the "hot" and "ground" wires.

2.- The phase supplying the power to the "split-phase" winding in the
secondary of home transformers is only ONE, there is no way to get more than
ONE phase out, even if formally the secondary winding could be measured
reversing the leads and appear as the negative value (hence the 180º figure)
Those two windings of the "split-phase system" are connected in such a way
as to provide a total voltage of 240V but could have been connected in
parallel to provide the double of current in one phase at 120V. Such
parallel connection would produce a "short" and high currents if in fact the
two windings were being driven by two distinct phases no matter what games
you play with the wire ends.

So, that's why any power engineer will raise an eyebrow if you address such
system with the clearly incorrect term of "two-phase system".

--
Mark Cross
If Linux doesn't have the solution, you have the wrong problem.

Jeffrey Angus wrote:

On 1/23/2011 9:05 AM, Jamie wrote:
Jeffrey Angus wrote:
It's single phase.

Jeff
Big JOKE!

You fail.

I bow to your superior logic and wit.


Look at his website before you concede.

http://webpages.charter.net/jamie_5/


--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

Phil Allison wrote:

"Bob AZ"

( snip tedious drivel)

But in no case, with the information presented here, is there any
method or device utilized to give any additional phases. One or two or
more. The hot legs are simply the same phase, transformed as needed,
added within the transformer, with the resultant two hot legs, 180
degrees out of phase with each other.

** A really beautiful example of "double think" if I ever saw one.

Three phase distribution starts with a generator with 3 sets of
windings that is distributed as three phase and utuilzed as needed.

** And if it had only 2 windings instead of 3 ??

Two AC waves would be produced simultaneously, remaining always 180 degrees
apart in phase and be completely * indistinguishable * from any other means
of creating the same situation.


If the generator had two windings, they would be 90 degrees out of
phase. It makes zero sense to have them at 180 degrees, since the
windings would have to share the slots, reducing the availible current
by half.



--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

These comments are logical and correct representations of the power system
that most of us use. For single phase motors, a 120VAC motor is a
single-phase motor, just as a 240VAC motor is referred to as a single-phase
motor, not a 2-phase motor because it's using 2 hot lines.

This issue is one that just gets argued endlessly by amateurs and intellects
to no end.. essentially a waste of useful time on an issue that's widely
misunderstood for all the wrong reasons.

Pick the issue apart just for sport, if you like, but the majority of
domestic power supplies are single-phase.. period.

Look anywhere you can for a New 2-phase motor.
The only individuals that would be describing a new motor as a 2-phase motor
will be some misguided trainee or someone taking advantage of your stupidity
of asking for one.

--
Cheers,
WB
..............


"Mark Cross" wrote in message
...
David Nebenzahl wrote:

A disagreement arose
thereafter about whether a center-tapped transformer actually delivers
two separate phases of electricity or not.

So, what do y'all say?

Formally, yes, there exist two phases set apart 180º. But formally also
that
is never called a "two-phase system".

Reasons:
1.- In polyphase system there is an usual understanding that phases are
different when you can not get the other phase by simple means other than
using transformers (or transformer arrays). In a 3 Phase system, there is
no
way to get a phase 120º away by adding, subtracting or switching cable
ends
of one phase. In a true two phase system, be it a three wire part of a 3
phase system or the Niagara example, there is no way to get the other
phase
(120º or 90º) by playing with the connections. In a "split phase" system,
the 180º phase is equal (in a balanced system) to the other one by just
exchanging the "hot" and "ground" wires.

2.- The phase supplying the power to the "split-phase" winding in the
secondary of home transformers is only ONE, there is no way to get more
than
ONE phase out, even if formally the secondary winding could be measured
reversing the leads and appear as the negative value (hence the 180º
figure)
Those two windings of the "split-phase system" are connected in such a way
as to provide a total voltage of 240V but could have been connected in
parallel to provide the double of current in one phase at 120V. Such
parallel connection would produce a "short" and high currents if in fact
the
two windings were being driven by two distinct phases no matter what games
you play with the wire ends.

So, that's why any power engineer will raise an eyebrow if you address
such
system with the clearly incorrect term of "two-phase system".

--
Mark Cross
If Linux doesn't have the solution, you have the wrong problem.

"Wild_Bill"


These comments are logical and correct representations of the power system
that most of us use. For single phase motors, a 120VAC motor is a
single-phase motor, just as a 240VAC motor is referred to as a
single-phase motor, not a 2-phase motor because it's using 2 hot lines.

** Massive straw man fallacy.

Why am I not surprised it comes from a ****ing TOP POSTER !!




..... Phil

On 1/23/2011 4:44 PM Wild_Bill spake thus:

These comments are logical and correct representations of the power system
that most of us use. For single phase motors, a 120VAC motor is a
single-phase motor, just as a 240VAC motor is referred to as a single-phase
motor, not a 2-phase motor because it's using 2 hot lines.

This issue is one that just gets argued endlessly by amateurs and intellects
to no end.. essentially a waste of useful time on an issue that's widely
misunderstood for all the wrong reasons.

I disagree entirely. Yes, in this case it's a semantic debate--what I
contend is actually 2-phase power (120-0-120 derived from a
center-tapped transformer) is not *called* that by the electric power
industry. It is, nonetheless, truly two phase power.

I think it's important because the idea of phases in electrical power is
an important one, even to a simpleton like the average electrician,
never mind the EE.

Example: if you're going to wire an Edison circuit (where two hots from
different phases, meaning different sides of the distribution panel, are
wired with a common neutral), you ought to understand electrical phases,
especially the consequences of two phases 180° apart. After all, that's
how the currents from the two sides cancel each other. Failure to grasp
such principles can, and do, lead to real-world consequences like
building fires.

Pick the issue apart just for sport, if you like, but the majority of
domestic power supplies are single-phase.. period.

Look anywhere you can for a New 2-phase motor.

Who said anything about a 2-phase motor? Nobody, so far as I can tell.

I'm saying that the ENTIRE DOMESTIC POWER SUPPLY FROM THE SECONDARY OF
THE POWER COMPANY'S TRANFORMER is 2-phase. Once you plug in a 120 volt
anything, or even many 240 volt anythings, you're only using one phase.
Sheesh.

The only individuals that would be describing a new motor as a 2-phase motor
will be some misguided trainee or someone taking advantage of your stupidity
of asking for one.

Again, where did this straw man come from?

Please notice that because of your non-standard top posting, any
previous replies have been cut off. Please do what 99% of others do here
and bottom post.


--
Comment on quaint Usenet customs, from Usenet:

To me, the *plonk...* reminds me of the old man at the public hearing
who stands to make his point, then removes his hearing aid as a sign
that he is not going to hear any rebuttals.

David Nebenzahl wrote:

On 1/23/2011 4:44 PM Wild_Bill spake thus:

These comments are logical and correct representations of the power
system that most of us use. For single phase motors, a 120VAC motor is
a single-phase motor, just as a 240VAC motor is referred to as a
single-phase motor, not a 2-phase motor because it's using 2 hot lines.

This issue is one that just gets argued endlessly by amateurs and
intellects to no end.. essentially a waste of useful time on an issue
that's widely misunderstood for all the wrong reasons.


I disagree entirely. Yes, in this case it's a semantic debate--what I
contend is actually 2-phase power (120-0-120 derived from a
center-tapped transformer) is not *called* that by the electric power
industry. It is, nonetheless, truly two phase power.

I think it's important because the idea of phases in electrical power is
an important one, even to a simpleton like the average electrician,
never mind the EE.

Example: if you're going to wire an Edison circuit (where two hots from
different phases, meaning different sides of the distribution panel, are
wired with a common neutral), you ought to understand electrical phases,
especially the consequences of two phases 180° apart. After all, that's
how the currents from the two sides cancel each other. Failure to grasp
such principles can, and do, lead to real-world consequences like
building fires.

Pick the issue apart just for sport, if you like, but the majority of
domestic power supplies are single-phase.. period.


Look anywhere you can for a New 2-phase motor.


Who said anything about a 2-phase motor? Nobody, so far as I can tell.

I'm saying that the ENTIRE DOMESTIC POWER SUPPLY FROM THE SECONDARY OF
THE POWER COMPANY'S TRANFORMER is 2-phase. Once you plug in a 120 volt
anything, or even many 240 volt anythings, you're only using one phase.
Sheesh.

The only individuals that would be describing a new motor as a 2-phase
motor will be some misguided trainee or someone taking advantage of
your stupidity of asking for one.


Again, where did this straw man come from?

Please notice that because of your non-standard top posting, any
previous replies have been cut off. Please do what 99% of others do here
and bottom post.



Don't waste your breath. it's not worth the effort.

Knowing that you understand it should be enough..

And by the way, I was looking at a 3 wire motor today, 2 phases of 180
apart with CT to operate it (3 wire motor). It was attached to a gear
box and only ran one direction, but you could use it as a stepper
(servo) or full out run. Most likely some custom motor for an application.

Jamie

Jamie, what info is included on the motor's data plate/label? Is there a
capacitance included, with a low value of 25uF or less?

I think you may have been looking at a PSC permanent split capacitor motor..
although I haven't seen any rated at 180V. Most 3-wire motors are PSC types.

BTW, PSC motors aren't defined or referred to as 2-phase motors.
They may be specified for some particular rating as single-direction motors,
but they are reversible, in fact, fast stopping/reversing is one of the
features of PSC motors.
The gearheads, and especially the right-angle gearheads with encoders
attached are very versatile.

--
Cheers,
WB
..............


"Jamie" t wrote in message
...

Don't waste your breath. it's not worth the effort.

Knowing that you understand it should be enough..

And by the way, I was looking at a 3 wire motor today, 2 phases of 180
apart with CT to operate it (3 wire motor). It was attached to a gear box
and only ran one direction, but you could use it as a stepper (servo) or
full out run. Most likely some custom motor for an application.

Jamie

On Sun, 23 Jan 2011 14:23:35 -0500 "Michael A. Terrell"
wrote in Message id:
:


Jeffrey Angus wrote:

On 1/23/2011 9:05 AM, Jamie wrote:
Jeffrey Angus wrote:
It's single phase.

Jeff
Big JOKE!

You fail.

I bow to your superior logic and wit.


Look at his website before you concede.

http://webpages.charter.net/jamie_5/

Ack! I almost went blind after seeing that pic on the right.

I should've included in the "Most 3-wire motors are PSC types" statement:
if the motors are not for 3-phase.

Just to be more specific (although 3-phase wasn't being included in the
topic).

--
Cheers,
WB
..............



"Wild_Bill" wrote in message
...
Jamie, what info is included on the motor's data plate/label? Is there a
capacitance included, with a low value of 25uF or less?

I think you may have been looking at a PSC permanent split capacitor
motor.. although I haven't seen any rated at 180V. Most 3-wire motors are
PSC types.

BTW, PSC motors aren't defined or referred to as 2-phase motors.
They may be specified for some particular rating as single-direction
motors, but they are reversible, in fact, fast stopping/reversing is one
of the features of PSC motors.
The gearheads, and especially the right-angle gearheads with encoders
attached are very versatile.

--
Cheers,
WB
.............


"Jamie" t wrote in
message ...

Don't waste your breath. it's not worth the effort.

Knowing that you understand it should be enough..

And by the way, I was looking at a 3 wire motor today, 2 phases of 180
apart with CT to operate it (3 wire motor). It was attached to a gear box
and only ran one direction, but you could use it as a stepper (servo) or
full out run. Most likely some custom motor for an application.

Jamie

JW wrote:

On Sun, 23 Jan 2011 14:23:35 -0500 "Michael A. Terrell"
wrote in Message id:
:


Jeffrey Angus wrote:

On 1/23/2011 9:05 AM, Jamie wrote:
Jeffrey Angus wrote:
It's single phase.

Jeff
Big JOKE!

You fail.

I bow to your superior logic and wit.


Look at his website before you concede.

http://webpages.charter.net/jamie_5/

Ack! I almost went blind after seeing that pic on the right.


Now you know not to listen to him.


--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

"David Nebenzahl" wrote in message
s.com...
I'm posting this to try to settle an argument going on in another
newsgroup (alt.home.repair) about phases in electrical power.
SNIP
And you have started another arguement here. haha..

Honestly this is a question that I have always had, and can't understand why
it isnt called 2 phase. Unless there is something to the picture I am
unaware of.

This qustion will enevetably be debated to the end of time. It is kind of
like discussing poloitcs or religion..

On 1/24/2011 7:40 PM Michael Kennedy spake thus:

"David Nebenzahl" wrote in message
s.com...

I'm posting this to try to settle an argument going on in another
newsgroup (alt.home.repair) about phases in electrical power.

SNIP And you have started another arguement here. haha..

Honestly this is a question that I have always had, and can't understand why
it isnt called 2 phase. Unless there is something to the picture I am
unaware of.

This qustion will enevetably be debated to the end of time. It is kind of
like discussing poloitcs or religion..

Well, it really shouldn't be like that. I mean, look, we're discussing a
well-known, measurable phenomenon. The output of the center-tapped
transformer can be demonstrated to supply two separate and distinct
phases. Hell, hook up two 'scopes and see what they show.

It's just that the 'lectric-heads--the lunks who install distribution
panels and such--won't let us *call* it "2-phase" for several dubious
reasons. Doesn't change the fact that it IS two-phase power. That's what
I'm getting at. I'm not trying to force anyone to change their
terminology or give up their superstitious beliefs; I know that that's
futile.


--
Comment on quaint Usenet customs, from Usenet:

To me, the *plonk...* reminds me of the old man at the public hearing
who stands to make his point, then removes his hearing aid as a sign
that he is not going to hear any rebuttals.

"David Nebenzahl" wrote in message
s.com...
On 1/24/2011 7:40 PM Michael Kennedy spake thus:

"David Nebenzahl" wrote in message
s.com...

I'm posting this to try to settle an argument going on in another
newsgroup (alt.home.repair) about phases in electrical power.

SNIP And you have started another arguement here. haha..

Honestly this is a question that I have always had, and can't understand
why it isnt called 2 phase. Unless there is something to the picture I am
unaware of.

This qustion will enevetably be debated to the end of time. It is kind of
like discussing poloitcs or religion..

Well, it really shouldn't be like that. I mean, look, we're discussing a
well-known, measurable phenomenon. The output of the center-tapped
transformer can be demonstrated to supply two separate and distinct
phases. Hell, hook up two 'scopes and see what they show.

It's just that the 'lectric-heads--the lunks who install distribution
panels and such--won't let us *call* it "2-phase" for several dubious
reasons. Doesn't change the fact that it IS two-phase power. That's what
I'm getting at. I'm not trying to force anyone to change their terminology
or give up their superstitious beliefs; I know that that's futile.



Unfortunately. Maybe we should more generic terminology to describe this.
There is a difference in the phase of the two legs off of a center tapped
transformer. This can not be argued. Anyone who argues so can go hook up a
couple scopes for themselves as you suggested.

Maybe the confusion exsists because of the nature of two seperate phase
(split phase) power vs 3. Correct me if I am wrong, but any device requiring
240V could be powered by 2 legs of a center tapped 7200V==120V N 120V
transformer or could be powered by a 7200V==240V transformer with the same
results.

That said Im sure someone will tell me why my theory of why this is a
confusion is wrong..

- Mike

"Michael Kennedy" mike@com wrote in message
...

"David Nebenzahl" wrote in message
s.com...
On 1/24/2011 7:40 PM Michael Kennedy spake thus:

"David Nebenzahl" wrote in message
s.com...

I'm posting this to try to settle an argument going on in another
newsgroup (alt.home.repair) about phases in electrical power.

SNIP And you have started another arguement here. haha..

Honestly this is a question that I have always had, and can't understand
why it isnt called 2 phase. Unless there is something to the picture I
am unaware of.

This qustion will enevetably be debated to the end of time. It is kind
of like discussing poloitcs or religion..

Well, it really shouldn't be like that. I mean, look, we're discussing a
well-known, measurable phenomenon. The output of the center-tapped
transformer can be demonstrated to supply two separate and distinct
phases. Hell, hook up two 'scopes and see what they show.

It's just that the 'lectric-heads--the lunks who install distribution
panels and such--won't let us *call* it "2-phase" for several dubious
reasons. Doesn't change the fact that it IS two-phase power. That's what
I'm getting at. I'm not trying to force anyone to change their
terminology or give up their superstitious beliefs; I know that that's
futile.



Unfortunately. Maybe we should more generic terminology to describe this.
There is a difference in the phase of the two legs off of a center tapped
transformer. This can not be argued. Anyone who argues so can go hook up a
couple scopes for themselves as you suggested.

Maybe the confusion exsists because of the nature of two seperate phase
(split phase) power vs 3. Correct me if I am wrong, but any device
requiring 240V could be powered by 2 legs of a center tapped 7200V==120V
N 120V transformer or could be powered by a 7200V==240V transformer with
the same results.

That said Im sure someone will tell me why my theory of why this is a
confusion is wrong..

- Mike

Hmm.. I must have not drank my coffee yet when I wrote this.. 3 phase would
operate the same way therefore making this all bunk.

Unfortunately. Maybe we should more generic terminology to
describe this. There is a difference in the phase of the two
legs off of a center tapped transformer. This can not be
argued. Anyone who argues so can go hook up a couple scopes for
themselves as you suggested.

Maybe the confusion exsists because of the nature of two
seperate phase (split phase) power vs 3. Correct me if I am
wrong, but any device requiring 240V could be powered by 2 legs
of a center tapped 7200V==120V N 120V transformer or could be
powered by a 7200V==240V transformer with the same results.

That said Im sure someone will tell me why my theory of why
this is a confusion is wrong..

- Mike

|Hmm.. I must have not drank my coffee yet when I wrote this.. 3
phase would
|operate the same way therefore making this all bunk.

Actually three phase service from the power company with the
phases 120 degrees apart, would work differently. In a 'Y'
connection if the voltage between the phases were X volts, the
voltage from one phase to neutral would be x/sqrt(3) rather than
x/2 as is the case with a center tapped transformer.

David

You're free to call it whatever you like.. and everyone that hears you call
single-phase items 2-phase instead, is free to find humor in it, or suspect
that you're uninformed, or lesser of you (without giving you any
indications).
Kinda like referring to an item with a perfectly practical/widely familar
name "a thingy", or a (something) thingy.

Superstitious would be applicable in the early years of the last century
when folks actually believed that distributed electricity was "fire on a
wire".
It was a mysterious power to be feared by many folks in backwoods/mountain
places in Appalachia for a significant portion of last century, and that
same term can be heard in documentary films of that area of the country.

Think what you like, but if you present yourself as being wiser or more
reasonable wrt the subject, it's essentially just trolling.. and since you
study proper usenet protocol, you know that's the equivalent to numerous
simultaneously performed deadly sins.

It's likely no one gives a FRA what you prefer to call single-phase,
however, many usenet folks will likely continue to attempt to correct you at
your use of the term 2-phase, primarily because it's not applicable to the
subject matter.. and just because 2-phase power is essentially non-existent.

As I suggested in my first reply in this thread.. essentially debated to
hell'n back, and still, there are still those defending the use of the term
2-phase.

--
Cheers,
WB
..............


"David Nebenzahl" wrote in message
s.com...

Well, it really shouldn't be like that. I mean, look, we're discussing a
well-known, measurable phenomenon. The output of the center-tapped
transformer can be demonstrated to supply two separate and distinct
phases. Hell, hook up two 'scopes and see what they show.

It's just that the 'lectric-heads--the lunks who install distribution
panels and such--won't let us *call* it "2-phase" for several dubious
reasons. Doesn't change the fact that it IS two-phase power. That's what
I'm getting at. I'm not trying to force anyone to change their terminology
or give up their superstitious beliefs; I know that that's futile.

Having a couple of decades experience in servicing/repair of commercial and
consumer electronic equipment and additional training and experience in
industrial site experience (both electrical and electronic circuits), I have
never seen descriptions or designations stated as 2-phase, for any type of
transformer.

Or: Hey bub, you gotta single-phase-in, 2-phase-out transformer?

But I have seen and used transformers with multiple taps, on both pri and
sec sides.
The number of taps on either side of a single-phase transformer don't change
the output(s) to 2-phase, regardless of how many there are (pri or sec
side).
Monophase sounds odd, like it's not related to electricity.
How about uniphase? Yep, found an example (and diphase) used in a book c
1905.
Electricity In Every-day Life Edwin J. Houston PhD. You know that's gonna be
interesting just because it was authored by a PhD.

--
Cheers,
WB
..............


"Michael Kennedy" wrote in message
...

Unfortunately. Maybe we should more generic terminology to describe this.
There is a difference in the phase of the two legs off of a center tapped
transformer. This can not be argued. Anyone who argues so can go hook up
a couple scopes for themselves as you suggested.

Maybe the confusion exsists because of the nature of two seperate phase
(split phase) power vs 3. Correct me if I am wrong, but any device
requiring 240V could be powered by 2 legs of a center tapped 7200V==120V
N 120V transformer or could be powered by a 7200V==240V transformer with
the same results.

That said Im sure someone will tell me why my theory of why this is a
confusion is wrong..

- Mike

Hmm.. I must have not drank my coffee yet when I wrote this.. 3 phase
would operate the same way therefore making this all bunk.