Two phases or not?

[Phil Allison]

"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

 

[Bob AZ]

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

 

[Jeffrey Angus]

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

 

[Jamie]

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.

 

[Mark Cross]

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 180Âş. 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 120Âş 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
(120Âş or 90Âş) by playing with the connections. In a "split phase" system,
the 180Âş 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 180Âş 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.

 

[Michael A. Terrell]

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.

 

[Michael A. Terrell]

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.

 

[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.

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" <markcross.gpg.01@gmx.com> wrote in message
news:2156246.bQZG1OUAWM@rnqqfki.new.org.invalid...

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 180Âş. 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 120Âş 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
(120Âş or 90Âş) by playing with the connections. In a "split phase" system,
the 180Âş 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 180Âş
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.

 

[Phil Allison]

"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 fucking TOP POSTER !!




..... Phil

 

[David Nebenzahl]

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.

 

[Jamie]

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

 

[Wild_Bill]

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" <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in message
news:de5%o.16039$TZ4.6414@newsfe20.iad...

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]

On Sun, 23 Jan 2011 14:23:35 -0500 "Michael A. Terrell"
<mike.terrell@earthlink.net> wrote in Message id:
<MaWdnaQtrvvZHaHQnZ2dnUVZ_oKdnZ2d@earthlink.com>:

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.

 

[Wild_Bill]

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" <wb_wildbill@XSPAMyahoo.com> wrote in message
news:j59%o.612113$De6.37826@en-nntp-01.dc1.easynews.com...

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" <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in
message news:de5%o.16039$TZ4.6414@newsfe20.iad...

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

 

[Michael A. Terrell]

JW wrote:

On Sun, 23 Jan 2011 14:23:35 -0500 "Michael A. Terrell"
mike.terrell@earthlink.net> wrote in Message id:
MaWdnaQtrvvZHaHQnZ2dnUVZ_oKdnZ2d@earthlink.com>:


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.

 

[Michael Kennedy]

"David Nebenzahl" <nobody@but.us.chickens> wrote in message
news:4d3a3c1e$0$31597$822641b3@news.adtechcomputers.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..

 

[David Nebenzahl]

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

"David Nebenzahl" <nobody@but.us.chickens> wrote in message
news:4d3a3c1e$0$31597$822641b3@news.adtechcomputers.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.

 

[Michael Kennedy]

"David Nebenzahl" <nobody@but.us.chickens> wrote in message
news:4d3e4a7b$0$21367$822641b3@news.adtechcomputers.com...

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

"David Nebenzahl" <nobody@but.us.chickens> wrote in message
news:4d3a3c1e$0$31597$822641b3@news.adtechcomputers.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]

"Michael Kennedy" <mike@com> wrote in message
news:bISdncmHWep_5qPQnZ2dnVY3goudnZ2d@giganews.com...

"David Nebenzahl" <nobody@but.us.chickens> wrote in message
news:4d3e4a7b$0$21367$822641b3@news.adtechcomputers.com...
On 1/24/2011 7:40 PM Michael Kennedy spake thus:

"David Nebenzahl" <nobody@but.us.chickens> wrote in message
news:4d3a3c1e$0$31597$822641b3@news.adtechcomputers.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.

 

[David]

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