Two phases or not?

[David Nebenzahl]

On 1/26/2011 7:45 PM Michael A. Terrell spake thus:

Michael Kennedy wrote:

MIke et al

The problem seems to be that after all this dialogue, that so
many of the responders simply don't stick to the basic premise
that different phases by definition have timing differences.
Simply reversing the way of using a phase does not make it a
different phase. The timing stays the same.

Ok I get what your saying.. But do you understand what a phanse difference
is?? It is timing like you said..

Here is an explanation using audio waves. Maybe you can get what I am
saying.

http://www.indiana.edu/~emusic/acoustics/phase.htm

By your definiton, a 'Push-Pull Output Transformer' is two phase.

It IS two phase; that's the whole point. (At least on the primary side.)

I'd be interested in your explanation of how it isn't ...

(I think my example was a little more clear: look at a center-tapped
transformer used as the input to a push-pull stage and tell me there
aren't two phases there.)


--
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.

 

[Wild_Bill]

Right.. let us all know when you find that 2-phase appliance/machine motor
for your 2-phase electrical service.

Ya Ignorant and apparently illiterate Cunt.. FOAD

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


"Jamie" <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in message
news:FP30p.3113$Y8.1462@newsfe06.iad...

Wild_Bill wrote:

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
.............

You still lose:

You don't seem to know the difference between circuits and phase
angles..

Typical residential hack electrician..

I hope you don't ever decide to move in to electronics, you'd be in a
world of shit.

 

[Michael A. Terrell]

David Nebenzahl wrote:

On 1/26/2011 7:45 PM Michael A. Terrell spake thus:

Michael Kennedy wrote:

MIke et al

The problem seems to be that after all this dialogue, that so
many of the responders simply don't stick to the basic premise
that different phases by definition have timing differences.
Simply reversing the way of using a phase does not make it a
different phase. The timing stays the same.

Ok I get what your saying.. But do you understand what a phanse difference
is?? It is timing like you said..

Here is an explanation using audio waves. Maybe you can get what I am
saying.

http://www.indiana.edu/~emusic/acoustics/phase.htm

By your definiton, a 'Push-Pull Output Transformer' is two phase.

It IS two phase; that's the whole point. (At least on the primary side.)

Then a Williamson 'Ultra linear' output transformer is four phase?

<http://www.pmillett.com/file_downloads/stancor_ul_schematics.pdf>

See page 4 for a sample schmatic.

I'd be interested in your explanation of how it isn't ...

(I think my example was a little more clear: look at a center-tapped
transformer used as the input to a push-pull stage and tell me there
aren't two phases there.)

Then look at a Williamson 'Ultra linear' output transformer and tell
me there are four phases.

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

 

[JW]

On Thu, 27 Jan 2011 00:23:25 +0000 (UTC) Meat Plow <mhywatt@yahoo.com>
wrote in Message id: <pan.2011.01.27.00.22.07@lmao.lol.lol>:

On Thu, 27 Jan 2011 11:19:54 +1100, Phil Allison wrote:


"Fred McKenzie"

"Phil Allison"

Sine waves of the exact same frequency and amplitude can ONLY differ
only in
phase.

A 180 degree phase difference is as good as any other.


I have a flashlight powered by a two-phase system - two D cells.


** Nuh - that is DC, you pathetic troll.


It certainly fits your criteria.


** Nuh - not one of them.


Its power system can also be considered AC, since DC is just AC with
frequency equal to zero.


** Just like white is the same as black with no lights on.


Facts are no deterrent to a persistent troll!


** Just like reality is no deterrent to a lunatic.

Did someone leave the door open at the asylum today ??

I'd make a comment here but it is against my new year's resolution.

My New Year's resolution was an easy one this year. Make no New Year's
resolutions ever again.

 

[Michael A. Terrell]

JW wrote:

On Thu, 27 Jan 2011 00:23:25 +0000 (UTC) Meat Plow <mhywatt@yahoo.com
wrote in Message id: <pan.2011.01.27.00.22.07@lmao.lol.lol>:

On Thu, 27 Jan 2011 11:19:54 +1100, Phil Allison wrote:


"Fred McKenzie"

"Phil Allison"

Sine waves of the exact same frequency and amplitude can ONLY differ
only in
phase.

A 180 degree phase difference is as good as any other.


I have a flashlight powered by a two-phase system - two D cells.


** Nuh - that is DC, you pathetic troll.


It certainly fits your criteria.


** Nuh - not one of them.


Its power system can also be considered AC, since DC is just AC with
frequency equal to zero.


** Just like white is the same as black with no lights on.


Facts are no deterrent to a persistent troll!


** Just like reality is no deterrent to a lunatic.

Did someone leave the door open at the asylum today ??

I'd make a comment here but it is against my new year's resolution.

My New Year's resolution was an easy one this year. Make no New Year's
resolutions ever again.

I made that one, over 30 years ago.


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

 

[Wild_Bill]

I didn't check the link.. the thread topic was electrical power.

I assume some of the fuckwits in this thread would like to argue that the
outputs of a simple stereo amp (L+/gnd and R+/gnd), with a center channel
(L+ and R+) would be 3-phase.

Still.. it's not electrical power.

A Simple, Practical and Sensible approach to the difference between
electrical circuits, and electronic circuits is:

Electrical power circuits perform work (mechanical energy, heat etc).

Electronic circuits are for relaying information (data, sensing, control of
electrical devices, communications).

I'm done here.. another wasted minute of my remaining time isn't worthwhile
to me.
Have yer fun.

As I suggested in my first reply in this thread, this issue is simply food
(a drug?) for the dimwitted that have nothing better to do.

I can only imagine the good efforts that could have been attributed to real
issues worldwide.. with the time/effort that's been wasted by trillions of
minutes of worthless usenet replies and pissing contests.

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


"Michael Kennedy" <mike@com> wrote in message
news:_4idndEDCOOWdd3QnZ2dnVY3goWdnZ2d@giganews.com...

MIke et al

The problem seems to be that after all this dialogue, that so many of
the responders simply don't stick to the basic premise that different
phases by definition have timing differences. Simply reversing the way
of using a phase does not make it a different phase. The timing stays
the same.


Ok I get what your saying.. But do you understand what a phanse
difference is?? It is timing like you said..

Here is an explanation using audio waves. Maybe you can get what I am
saying.

http://www.indiana.edu/~emusic/acoustics/phase.htm

 

[Bob AZ]

Ok I get what your saying.. But do you understand what a  phanse difference
is?? It is timing like you said.

Mike

Nice weblink. Someone went to a lot of work to do the programming and
all for it. When I had phase and rotation and the resultants presented
to me a long time ago it was on a blackboard by a math person. Took a
while to sink in with all of us in the class.

I do undrstand what a phase difference is. I have been tripped up lots
of times by it. One time that comes to my mind was when I was working
in a 3 phase box and simply couldn't get a there phase subpanel to
give me three hot legs as I expected. I found out that a major airport
used nothing but 3 phase panels for distribution but only distributed
two phases of the three. They used the vacant pole in the panel for
growth. There was even a mix of 110 and 220 volts. Thus the panel had
one phase on the first pole and the other poles were the same phase.
Cost the US government a few thousand which was recovered from the
municipality with penalties.

And to "add" to this discussion I am filtering the responses by my
personal criteria. There are 3 ways of doing anything. The adult way,
the child way and the infant way. Take a look at some of the
responses. Civil and not so civil. Our leaders thrust on "civility" is
long over due.

Bob AZ

 

[David Nebenzahl]

On 1/27/2011 12:29 AM Michael A. Terrell spake thus:

David Nebenzahl wrote:

On 1/26/2011 7:45 PM Michael A. Terrell spake thus:

Michael Kennedy wrote:

MIke et al

The problem seems to be that after all this dialogue, that so
many of the responders simply don't stick to the basic
premise that different phases by definition have timing
differences. Simply reversing the way of using a phase does
not make it a different phase. The timing stays the same.

Ok I get what your saying.. But do you understand what a phanse

difference
is?? It is timing like you said..

Here is an explanation using audio waves. Maybe you can get
what I am saying.

http://www.indiana.edu/~emusic/acoustics/phase.htm

By your definiton, a 'Push-Pull Output Transformer' is two
phase.

It IS two phase; that's the whole point. (At least on the primary side.)

Then a Williamson 'Ultra linear' output transformer is four phase?

http://www.pmillett.com/file_downloads/stancor_ul_schematics.pdf

See page 4 for a sample schmatic.

I looked at your Stancor PDF. Why in the world would you think I'd think
that transformer is 4-phase???

[btw, the schematics are on pages 2 and 6]

OK, I'll play along here. On page 6 they show an output xfmr with 2
taps. But of course that has nothing whatever to do with phase, as you
damn well know, because the output is referenced to one of the OUTER
LEGS OF THE TRANSFORMER (see that "COM" on the bottom?), so the output
is simply one phase. I was talking about a center-tapped transformer
where the two sides are referenced to THE CENTER TAP.

So again, how does a center-tapped transformer secondary WHERE THE
OUTPUT IS REFERENCED TO THE CENTER TAP (i.e., the center tap is
grounded) NOT generate two separate phases? Please 'splain 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.

 

[William Sommerwerck]

How does a center-tapped transformer secondary WHERE
THE OUTPUT IS REFERENCED TO THE CENTER TAP
(ie, the center tap is grounded) NOT generate two separate
phases?

After thinking about this, I've come to the conclusion that it doesn't.

"Phase" implies a relative-timing relationship. Simply inverting polarity
doesn't change the timing between the two waveforms.

 

[Bill K7NOM]

William Sommerwerck wrote:

How does a center-tapped transformer secondary WHERE
THE OUTPUT IS REFERENCED TO THE CENTER TAP
(ie, the center tap is grounded) NOT generate two separate
phases?

After thinking about this, I've come to the conclusion that it doesn't.

"Phase" implies a relative-timing relationship. Simply inverting polarity
doesn't change the timing between the two waveforms.


If you compare the timing of the positive part of the sine wave you will

see that the two signals have different timing.

Bill K7NOM

 

[William Sommerwerck]

"Bill K7NOM" <billj@ieee.org> wrote in message
news:rnC0p.58707$be.1929@newsfe05.iad...

William Sommerwerck wrote:

How does a center-tapped transformer secondary WHERE
THE OUTPUT IS REFERENCED TO THE CENTER TAP
(ie, the center tap is grounded) NOT generate two separate
phases?

After thinking about this, I've come to the conclusion that it doesn't.
"Phase" implies a relative-timing relationship. Simply inverting polarity
doesn't change the timing between the two waveforms.

If you compare the timing of the positive part of the sine wave you will
see that the two signals have different timing.

No more than your image in a mirror is a separate being.

 

[David Nebenzahl]

On 1/28/2011 6:38 AM William Sommerwerck spake thus:

How does a center-tapped transformer secondary WHERE
THE OUTPUT IS REFERENCED TO THE CENTER TAP
(ie, the center tap is grounded) NOT generate two separate
phases?

After thinking about this, I've come to the conclusion that it doesn't.

"Phase" implies a relative-timing relationship. Simply inverting polarity
doesn't change the timing between the two waveforms.

That can't be correct.

Let's test the hypothesis. If we had two signals that were 179° out of
phase, would you not say that we had two separate phases? There is a
definite, though small, timing difference.

Let's say the signals were 181° out of phase: two phases again, correct?

So what's "special" or magic about 180° that it wouldn't be considered a
completely separate and distinct phase? Why would phase have a "hole" at
180°? (And for any wisenheimers who will say "well, you must consider 0°
to be a separate phase too!" I say nonsense: that's just a phase
"identity" which we can ignore as being identical to the original phase.)

People seem to be tripped up by the fact that it's trivially easy to
produce the 180° phase, and that it is, as you say, a mirror image of
its respective phase. But this doesn't make it any less of a separate phase.

The other fallacy here is that because we don't actually use 2-phase
electrical power, there cannot be any such thing as 2-phase power. It is
true that two phase power (0° - 180°) is not very useful; that's why we
don't have any 2-phase motors. But technically, a system with two legs
of 0° and 180° is, in fact, a 2-phase system.

Even if it's not called that. Even if it is not used *as a phased
system* (it's used to derive two legs from a step-down transformer in a
120-0-120 arrangement). It's still 2-phase power.

So whaddya say now?


--
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.

 

[Mark Cross]

David Nebenzahl wrote:

On 1/28/2011 6:38 AM William Sommerwerck spake thus:

How does a center-tapped transformer secondary WHERE
THE OUTPUT IS REFERENCED TO THE CENTER TAP
(ie, the center tap is grounded) NOT generate two separate
phases?

After thinking about this, I've come to the conclusion that it doesn't.

"Phase" implies a relative-timing relationship. Simply inverting polarity
doesn't change the timing between the two waveforms.

That can't be correct.

Let's test the hypothesis. If we had two signals that were 179° out of
phase, would you not say that we had two separate phases? There is a
definite, though small, timing difference.

Let's say the signals were 181° out of phase: two phases again, correct?

So what's "special" or magic about 180° that it wouldn't be considered a
completely separate and distinct phase? Why would phase have a "hole" at
180°? (And for any wisenheimers who will say "well, you must consider 0°
to be a separate phase too!" I say nonsense: that's just a phase
"identity" which we can ignore as being identical to the original phase.)

Repeat the hypothesis a 0Âş and you will find a hole in there, much the same
as there must be one at 180Âş.

To understand what is "magical" about that you will need to know phasors and
the math related to that. Once you understand the math that support phasors,
you clearly see why 0Âş and 180Âş are the same phasor.

http://en.wikipedia.org/wiki/Phasor

People seem to be tripped up by the fact that it's trivially easy to
produce the 180° phase, and that it is, as you say, a mirror image of
its respective phase. But this doesn't make it any less of a separate
phase.

The other fallacy here is that because we don't actually use 2-phase
electrical power, there cannot be any such thing as 2-phase power. It is
true that two phase power (0° - 180°) is not very useful; that's why we
don't have any 2-phase motors. But technically, a system with two legs
of 0° and 180° is, in fact, a 2-phase system.

Even if it's not called that. Even if it is not used *as a phased
system* (it's used to derive two legs from a step-down transformer in a
120-0-120 arrangement). It's still 2-phase power.

So whaddya say now?

No, it isn't.

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

 

[David Nebenzahl]

On 1/28/2011 11:19 AM David Nebenzahl spake thus:

The other fallacy here is that because we don't actually use 2-phase
electrical power, there cannot be any such thing as 2-phase power. It is
true that two phase power (0° - 180°) is not very useful; that's why we
don't have any 2-phase motors. But technically, a system with two legs
of 0° and 180° is, in fact, a 2-phase system.

Actually, there is at least one application which depends on there being
2 phases in ordinary residential power distribution panels: the
so-called Edison circuit. This is where two circuits are run with
separate "hots" and a common neutral, where the neutral conductor is the
same size as the hots.

The only way this can work is if the two circuits are separate phases
(in this case, 180° apart), so that the currents cancel in the common
return conductor.

Apart from this, we wouldn't care if the two legs of the power company's
step-down transformer delivered the same phase of power (just give us
the juice! who cares about the phase?).


--
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.

 

[Phil Allison]

"William Sommerwerck"

"Phase" implies a relative-timing relationship.

** The term " phase shift " generally has that implication - but not the
term " phase " alone.

Simply inverting polarity doesn't change the timing between the two
waveforms.

** Irrelevant - see above.

In any case, for continuous sinewaves a 180 degree phase shift and signal
polarity inversion are completely indistinguishable.



..... Phil

 

[David Nebenzahl]

On 1/28/2011 11:28 AM Mark Cross spake thus:

David Nebenzahl wrote:

So what's "special" or magic about 180° that it wouldn't be considered a
completely separate and distinct phase? Why would phase have a "hole" at
180°? (And for any wisenheimers who will say "well, you must consider 0°
to be a separate phase too!" I say nonsense: that's just a phase
"identity" which we can ignore as being identical to the original phase.)

Repeat the hypothesis a 0Âş and you will find a hole in there, much the same
as there must be one at 180Âş.

I don't think so. At 0Âş, the two waveforms are *identical*, so that's
the degenerate case.

To understand what is "magical" about that you will need to know phasors and
the math related to that. Once you understand the math that support phasors,
you clearly see why 0Âş and 180Âş are the same phasor.

http://en.wikipedia.org/wiki/Phasor

Sorry, I don't use Wikipedia as a source of credible information.

But even if 0Âş and 180Âş are the same phasor, they're still completely
different waveforms, which is the important thing here, isn't 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.

 

[Mark Cross]

David Nebenzahl wrote:

On 1/28/2011 11:28 AM Mark Cross spake thus:

David Nebenzahl wrote:

So what's "special" or magic about 180° that it wouldn't be considered a
completely separate and distinct phase? Why would phase have a "hole" at
180°? (And for any wisenheimers who will say "well, you must consider 0°
to be a separate phase too!" I say nonsense: that's just a phase
"identity" which we can ignore as being identical to the original
phase.)

Repeat the hypothesis a 0Âş and you will find a hole in there, much the
same as there must be one at 180Âş.

I don't think so. At 0Âş, the two waveforms are *identical*, so that's
the degenerate case.

To understand what is "magical" about that you will need to know phasors
and the math related to that. Once you understand the math that support
phasors, you clearly see why 0Âş and 180Âş are the same phasor.

http://en.wikipedia.org/wiki/Phasor

Sorry, I don't use Wikipedia as a source of credible information.

Open your mind.

But even if 0Âş and 180Âş are the same phasor, they're still completely
different waveforms, which is the important thing here, isn't it?

No.

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

 

[bud--]

David Nebenzahl wrote:

On 1/28/2011 11:28 AM Mark Cross spake thus:

David Nebenzahl wrote:

So what's "special" or magic about 180° that it wouldn't be considered a
completely separate and distinct phase? Why would phase have a "hole" at
180°? (And for any wisenheimers who will say "well, you must consider 0°
to be a separate phase too!" I say nonsense: that's just a phase
"identity" which we can ignore as being identical to the original
phase.)

So you get 2 phases out of a single phase power transformer?
With 2 separate secondary windings there are 2 phases. Winding A is not
the same as winding B.

With 3 separate secondary windings there are 3 separate phases. Winding
A is not the same as winding B. And winding C is not the same as A. And
C is not the same as B.

With 4 separate secondary windings there are 4 phases. ....

Your transformer supplier can furnish a single core transformer with 4
secondary phases?
Your transformer supplier can furnish a single-core transformer with 2
secondary phases?

To understand what is "magical" about that you will need to know
phasors and the math related to that. Once you understand the math
that support phasors, you clearly see why 0Âş and 180Âş are the same
phasor.

http://en.wikipedia.org/wiki/Phasor

Sorry, I don't use Wikipedia as a source of credible information.

Then use your own knowledge of phasors. The representation of a 120/240V
service (relative to N) is +120 and -120, both real. There are no
imaginary components. Plus and minus relationships.

But even if 0Âş and 180Âş are the same phasor, they're still completely
different waveforms, which is the important thing here, isn't it?

Completely different waveforms? Plus sine is a completely different
waveform from minus sine. Have you taken trigonometry? On a transformer
secondary the relative relationships are locked at plus or minus. 180
degrees is trivial.

When you are doing calculations on a simple single-phase resistive
system you use phase angles? Most of us use plus and minus signs. With
non-resistive elements phasors are used - see above.

You can, of course, call it whatever you want to. Just expect
communication problems. I remember 2 people here who agree with you. It
is not the only 2 people I would want agreeing with me. Maybe you could
shop around to a different newsgroup - maybe alt.engineering.electrical?


And two-phase does still exist. Some relatively small 3-phase to 3-phase
transformers (like 480/277 to 208/120) connect 2 transformers in a Scott
(T) connection. The transformers are an intermediate 2-phase. That is,
real 2-phase - 90 degrees between the voltages

--
bud--

 

[Jamie]

bud-- wrote:

David Nebenzahl wrote:

On 1/28/2011 11:28 AM Mark Cross spake thus:

David Nebenzahl wrote:

So what's "special" or magic about 180° that it wouldn't be
considered a
completely separate and distinct phase? Why would phase have a
"hole" at
180°? (And for any wisenheimers who will say "well, you must
consider 0°
to be a separate phase too!" I say nonsense: that's just a phase
"identity" which we can ignore as being identical to the original
phase.)


So you get 2 phases out of a single phase power transformer?
With 2 separate secondary windings there are 2 phases. Winding A is not
the same as winding B.

With 3 separate secondary windings there are 3 separate phases. Winding
A is not the same as winding B. And winding C is not the same as A. And
C is not the same as B.

With 4 separate secondary windings there are 4 phases. ....

Your transformer supplier can furnish a single core transformer with 4
secondary phases?
Your transformer supplier can furnish a single-core transformer with 2
secondary phases?


To understand what is "magical" about that you will need to know
phasors and the math related to that. Once you understand the math
that support phasors, you clearly see why 0Âş and 180Âş are the same
phasor.

http://en.wikipedia.org/wiki/Phasor


Sorry, I don't use Wikipedia as a source of credible information.


Then use your own knowledge of phasors. The representation of a 120/240V
service (relative to N) is +120 and -120, both real. There are no
imaginary components. Plus and minus relationships.


But even if 0Âş and 180Âş are the same phasor, they're still
completely different waveforms, which is the important thing here,
isn't it?



Completely different waveforms? Plus sine is a completely different
waveform from minus sine. Have you taken trigonometry? On a transformer
secondary the relative relationships are locked at plus or minus. 180
degrees is trivial.

When you are doing calculations on a simple single-phase resistive
system you use phase angles? Most of us use plus and minus signs. With
non-resistive elements phasors are used - see above.

You can, of course, call it whatever you want to. Just expect
communication problems. I remember 2 people here who agree with you. It
is not the only 2 people I would want agreeing with me. Maybe you could
shop around to a different newsgroup - maybe alt.engineering.electrical?


And two-phase does still exist. Some relatively small 3-phase to 3-phase
transformers (like 480/277 to 208/120) connect 2 transformers in a Scott
(T) connection. The transformers are an intermediate 2-phase. That is,
real 2-phase - 90 degrees between the voltages

Yes, 2 phase of 90 degree's still exist, so why is that ok but 180

degree's isn't?

Look at power generators (portables), most of them have 2 circuits
from the generator 180 out from each other.. Why is this any different
from a
generator of 90 degrees out ? You can combine a leg of each output from
a those generators also..

It's argument that you won't win from those that truly understand the
meaning of phase angle supplies and the number of supply legs.

Its clear that the maximum you can obtain is only 2 phase angles from
any combination of CT's on a transformer supplied from a single phase
leg how ever, the number of circuits from a transformer can be endless
but not practical, of course.

 

[Michael A. Terrell]

Jamie wrote:

bud-- wrote:

David Nebenzahl wrote:

On 1/28/2011 11:28 AM Mark Cross spake thus:

David Nebenzahl wrote:

So what's "special" or magic about 180° that it wouldn't be
considered a
completely separate and distinct phase? Why would phase have a
"hole" at
180°? (And for any wisenheimers who will say "well, you must
consider 0°
to be a separate phase too!" I say nonsense: that's just a phase
"identity" which we can ignore as being identical to the original
phase.)


So you get 2 phases out of a single phase power transformer?
With 2 separate secondary windings there are 2 phases. Winding A is not
the same as winding B.

With 3 separate secondary windings there are 3 separate phases. Winding
A is not the same as winding B. And winding C is not the same as A. And
C is not the same as B.

With 4 separate secondary windings there are 4 phases. ....

Your transformer supplier can furnish a single core transformer with 4
secondary phases?
Your transformer supplier can furnish a single-core transformer with 2
secondary phases?


To understand what is "magical" about that you will need to know
phasors and the math related to that. Once you understand the math
that support phasors, you clearly see why 0Âş and 180Âş are the same
phasor.

http://en.wikipedia.org/wiki/Phasor


Sorry, I don't use Wikipedia as a source of credible information.


Then use your own knowledge of phasors. The representation of a 120/240V
service (relative to N) is +120 and -120, both real. There are no
imaginary components. Plus and minus relationships.


But even if 0Âş and 180Âş are the same phasor, they're still
completely different waveforms, which is the important thing here,
isn't it?



Completely different waveforms? Plus sine is a completely different
waveform from minus sine. Have you taken trigonometry? On a transformer
secondary the relative relationships are locked at plus or minus. 180
degrees is trivial.

When you are doing calculations on a simple single-phase resistive
system you use phase angles? Most of us use plus and minus signs. With
non-resistive elements phasors are used - see above.

You can, of course, call it whatever you want to. Just expect
communication problems. I remember 2 people here who agree with you. It
is not the only 2 people I would want agreeing with me. Maybe you could
shop around to a different newsgroup - maybe alt.engineering.electrical?


And two-phase does still exist. Some relatively small 3-phase to 3-phase
transformers (like 480/277 to 208/120) connect 2 transformers in a Scott
(T) connection. The transformers are an intermediate 2-phase. That is,
real 2-phase - 90 degrees between the voltages

Yes, 2 phase of 90 degree's still exist, so why is that ok but 180
degree's isn't?

Look at power generators (portables), most of them have 2 circuits
from the generator 180 out from each other.. Why is this any different
from a
generator of 90 degrees out ? You can combine a leg of each output from
a those generators also..

It's argument that you won't win from those that truly understand the
meaning of phase angle supplies and the number of supply legs.

Its clear that the maximum you can obtain is only 2 phase angles from
any combination of CT's on a transformer supplied from a single phase
leg how ever, the number of circuits from a transformer can be endless
but not practical, of course.

This, from an illiterate ham radio junkie?


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