On 12/01/2013 09:57 PM, Tony Hwang wrote:

[snip]

Today's young engineers hardly do manual calculations. They just tap the
keys on computer. When I showed my son old slide ruler i used to use,
the look on his face....He is a consulting engineer in civil.

I remember the first class I had in trigonometry. Most of the time, the
teacher was going around helping students find the (sin / cos / tan)
keys on their calculators. There was nothing said about what
trigonometry is, or why you'd want to use it (other than passing that test).

--
23 days until The winter celebration (Wednesday December 25, 2013 12:00
AM for 1 day).

Mark Lloyd
http://notstupid.us

"Science is a first-rate piece of furniture for a man's upper chamber,
if he has common sense on the ground floor." [Oliver Wendell Holmes]

"Tony Hwang" wrote in message news:YyTmu.271050

Today's young engineers hardly do manual calculations. They just tap the
keys on computer. When I showed my son old slide ruler i used to use,
the look on his face....He is a consulting engineer in civil.

stuff snipped

I have a great old Pickett circular slide rule that had two plastic index
arms that would set to the numbers you were working with. IIRC, it was more
accurate than a twelve inch slide rule but only on the outermost scales. I
have a number of those - plastic, bamboo and aluminum -as well as
beautifully chromed K&E drafting sets that are all pretty much obsolete. I
still use vernier calipers and the B&S micrometer that I bought way back
then, but all the protracters, triangles, french curves, lettering guides
and Rapidographs are lying in a box somewhere, mouldering.

There's something that a slide rule teaches you about the elements of
mathematical relationships that you just can't get from a computer.

--
Bobby G.

On 12/1/13 9:31 AM, Emma Genius wrote:

Here's what my genius mind came up with.

First I obtained a standard D-cell battery pack that holds 2 batteries
in series.

Next I installed a center tap between the two batteries in the battery
pack.

So now I have a series battery pack with three terminals:

L1 is the (-) negative terminal on battery A
N is the center or neutral tap between battery A and B
L2 is the (+) positive terminal on battery B

So to prove I have 2-phase DC, I connected a dual-trace oscilloscope as
follows:

The reference leads from both probes were connected to the center
neutral tap.
Probe A was connected to L1
Probe B was connected to L2

As I expected, the scope showed a 1.5 volt positive phase trace and a
1.5 volt negative phase trace.

Clearly I have 3 volt 2 phase DC.

The only thing left to do is submit my paper to IEEE.


Suppose you wanted to run an irrigation system that requires three
phase, 480 to operate. Suppose the local rural power company could only
supply you with single phase 480. Suppose Emma Genius then built a
rotary phase converter to make that three phase load run from single
phase.
Suppose that rotary phase converter created only the third leg of
the three phase to operate the three phase load. Where did the other
two necessary phases originate to operate that three phase load?

On Monday, December 2, 2013 6:05:15 PM UTC-5, Dean Hoffman wrote:
On 12/1/13 9:31 AM, Emma Genius wrote:



Here's what my genius mind came up with.



First I obtained a standard D-cell battery pack that holds 2 batteries

in series.



Next I installed a center tap between the two batteries in the battery

pack.



So now I have a series battery pack with three terminals:



L1 is the (-) negative terminal on battery A

N is the center or neutral tap between battery A and B

L2 is the (+) positive terminal on battery B



So to prove I have 2-phase DC, I connected a dual-trace oscilloscope as

follows:



The reference leads from both probes were connected to the center

neutral tap.

Probe A was connected to L1

Probe B was connected to L2



As I expected, the scope showed a 1.5 volt positive phase trace and a

1.5 volt negative phase trace.



Clearly I have 3 volt 2 phase DC.



The only thing left to do is submit my paper to IEEE.





Suppose you wanted to run an irrigation system that requires three

phase, 480 to operate. Suppose the local rural power company could only

supply you with single phase 480. Suppose Emma Genius then built a

rotary phase converter to make that three phase load run from single

phase.

Suppose that rotary phase converter created only the third leg of

the three phase to operate the three phase load. Where did the other

two necessary phases originate to operate that three phase load?

I'm still waiting for one of the "experts" to give us their
definition of phase. They've been talking about it for a week now,
but not one will define it.

I'm also waiting for a response to the two phase student excercise
I posted earlier. They all seem to agree that two phase existed
100 years ago. They have no problem with it being called two
phase, that was the only legitimat two phase according to them.
So, that system had two phases, let's call them A and B
and a neutral. Phase B was 90 deg off from phase A. Everyone OK
so far?

Now, instead of having phase B be off by 90 degrees, let's make it
off by 120 deg. How many phases are there now? I say two. Let's
change it again, so phase B is off by 220 degrees. How many phases
do we have now? I say two. Let's change it to being off by 170 deg,
how many phases do we have now? I say two. And now, let's change
it to be off by 180 deg. How many phases do we have now? I say
two. And if it they agree that it is indeed still two, then it
is in fact electrically identical to split-phase 240/120V service,
so you have two phases there too.

QED

On Mon, 02 Dec 2013 15:27:10 -0600, Mark Lloyd
wrote:

On 12/01/2013 09:57 PM, Tony Hwang wrote:

[snip]

Today's young engineers hardly do manual calculations. They just tap the
keys on computer. When I showed my son old slide ruler i used to use,
the look on his face....He is a consulting engineer in civil.

I remember the first class I had in trigonometry. Most of the time, the
teacher was going around helping students find the (sin / cos / tan)
keys on their calculators. There was nothing said about what
trigonometry is, or why you'd want to use it (other than passing that test).

You do sin/cos/tan functions by hand? ;-)

I've only taken one trig class - 8 weeks (half a semester) in high
school. They used the "unit circle" method, which was quite a good
method of teaching. Understanding is much easier then mindless
memorization and lasts longer.

On Mon, 02 Dec 2013 17:05:15 -0600, Dean Hoffman
" wrote:

On 12/1/13 9:31 AM, Emma Genius wrote:

Here's what my genius mind came up with.

First I obtained a standard D-cell battery pack that holds 2 batteries
in series.

Next I installed a center tap between the two batteries in the battery
pack.

So now I have a series battery pack with three terminals:

L1 is the (-) negative terminal on battery A
N is the center or neutral tap between battery A and B
L2 is the (+) positive terminal on battery B

So to prove I have 2-phase DC, I connected a dual-trace oscilloscope as
follows:

The reference leads from both probes were connected to the center
neutral tap.
Probe A was connected to L1
Probe B was connected to L2

As I expected, the scope showed a 1.5 volt positive phase trace and a
1.5 volt negative phase trace.

Clearly I have 3 volt 2 phase DC.

The only thing left to do is submit my paper to IEEE.


Suppose you wanted to run an irrigation system that requires three
phase, 480 to operate. Suppose the local rural power company could only
supply you with single phase 480. Suppose Emma Genius then built a
rotary phase converter to make that three phase load run from single
phase.
Suppose that rotary phase converter created only the third leg of
the three phase to operate the three phase load. Where did the other
two necessary phases originate to operate that three phase load?

It's quite simple. The rotary phase converter is a generator.

On Mon, 02 Dec 2013 15:50:47 -0800, wrote:
I say
two. And if it they agree that it is indeed still two, then it
is in fact electrically identical to split-phase 240/120V service,
so you have two phases there too.

QED


All you are doing is reversing the leads on your scope to get a fake second phase.

Your cheap trick will only fool an imbecile.

On 12/02/2013 06:05 PM, Dean Hoffman wrote:
Suppose you wanted to run an irrigation system that requires three phase, 480 to operate. Suppose the local rural power company could only supply you with single phase 480. Suppose Emma Genius then built a rotary phase converter to make that three phase load run from single phase.
Suppose that rotary phase converter created only the third leg of the three phase to operate the three phase load. Where did the other two necessary phases originate to operate that three phase load?

I don't know about you and Emma but I'd send that piece-of-**** rotary phase converter back to China Harbor Fright and get a proper one from www.americanrotary.com .

On Monday, December 2, 2013 8:29:20 PM UTC-5, Edwin wrote:
On Mon, 02 Dec 2013 15:50:47 -0800, wrote:

I say

two. And if it they agree that it is indeed still two, then it

is in fact electrically identical to split-phase 240/120V service,

so you have two phases there too.



QED





All you are doing is reversing the leads on your scope to get a fake second phase.



Your cheap trick will only fool an imbecile.

Complete inability to address the simple and carefully outlined learning excercise I gave, noted. Inability to even define the term "phase", as requested noted. As is the name calling which is what you're left with
when you don't have engineering or the facts on your side. And for the
record, a scope wasn't even involved.

I can't remember whether my old Hughes Owens slide rule had trig functions on it or not. It seems to me that it didn't.

Back before there were calculators, engineers would carry around a book called the CRC Handbook, published by the Chemical Rubber Company, whoever that was. That book had tables for squares, square roots, cubes, cube roots, trig functions, hyperbolic trig fuctions, etc. You would use those tables to find the values of trig functions if you knew the angle expressed in degrees or radians.

No one ever worked out trig functions by hand, although you could do it. There were Taylor series solutions developed for all the trig functions, and the computers of the time used those series approximations to generate sine, cosine, and tangent. For example, the Taylor series for exponential of x, sine of x and cosine of x a

exp(x) = 1 + x + x2/2! + x3/3! + x4/4! + ...

sin(x) = x - x3/3! + x5/5! - x7/7! + x9/9! - ...

cos(x) = 1 - x2/2! + x4/4! - x6/6! + x8/8! - ...

where x3 means x cubed, or X times X times X, and the exclamation mark means "factorial". for example: 8! = 8 X 7 X 6 X 5 X 4 X 3 X 2 X 1 = 40320

So, you can do trig functions by hand, but the way you do them lends itself better to computer calculation.

On 12/03/2013 01:03 AM, wrote:
On Monday, December 2, 2013 8:29:20 PM UTC-5, Edwin wrote:
On Mon, 02 Dec 2013 15:50:47 -0800, wrote:

I say

two. And if it they agree that it is indeed still two, then it

is in fact electrically identical to split-phase 240/120V service,

so you have two phases there too.



QED





All you are doing is reversing the leads on your scope to get a fake second phase.



Your cheap trick will only fool an imbecile.

Complete inability to address the simple and carefully outlined learning excercise I gave, noted. Inability to even define the term "phase", as requested noted. As is the name calling which is what you're left with
when you don't have engineering or the facts on your side. And for the
record, a scope wasn't even involved.


I need a new furnace. Are two phase furnaces more efficient and where can I get one?

On Tuesday, December 3, 2013 5:04:51 AM UTC-5, ralph wrote:
On 12/03/2013 01:03 AM, wrote:

On Monday, December 2, 2013 8:29:20 PM UTC-5, Edwin wrote:

On Mon, 02 Dec 2013 15:50:47 -0800, wrote:



I say



two. And if it they agree that it is indeed still two, then it



is in fact electrically identical to split-phase 240/120V service,



so you have two phases there too.







QED











All you are doing is reversing the leads on your scope to get a fake second phase.







Your cheap trick will only fool an imbecile.



Complete inability to address the simple and carefully outlined learning excercise I gave, noted. Inability to even define the term "phase", as requested noted. As is the name calling which is what you're left with

when you don't have engineering or the facts on your side. And for the

record, a scope wasn't even involved.





I need a new furnace. Are two phase furnaces more efficient and where can I get one?

Again, complete avoidance of the intellectual excercise on phase I outlined above noted. No answer to the simple question of giving a definition of the engineering term "phase" noted. Smart remarks don't build a case.

I can define it. And I'm still waiting for an answer why a system with
two phases that differ by 90 deg is acknowledged by everyone to have two
phases. If they differ by 240 deg, that's two phase right? If they
differ by 170 deg, that must be two phases, right? So, what magically
happens when they differ by 180 deg that suddenly there are no longer two
phases? And how do the electrons know?

On 12/3/2013 8:25 AM, wrote:

And I'm still waiting for an answer why a system with
two phases that differ by 90 deg is acknowledged by everyone to have two
phases. If they differ by 240 deg, that's two phase right? If they
differ by 170 deg, that must be two phases, right? So, what magically
happens when they differ by 180 deg that suddenly there are no longer two
phases? And how do the electrons know?


For a garden variety split-phase supply (240/120V from a transformer
with a centertap) are there 2 "phases"?

On Tuesday, December 3, 2013 12:07:05 PM UTC-5, bud-- wrote:
On 12/3/2013 8:25 AM, wrote:



And I'm still waiting for an answer why a system with

two phases that differ by 90 deg is acknowledged by everyone to have two

phases. If they differ by 240 deg, that's two phase right? If they

differ by 170 deg, that must be two phases, right? So, what magically

happens when they differ by 180 deg that suddenly there are no longer two

phases? And how do the electrons know?





For a garden variety split-phase supply (240/120V from a transformer

with a centertap) are there 2 "phases"?



Non-response to the simple thought excercise on phase, going from
what everyone agrees is two phase, to what is electrically identical
to the 240/120V split-phase service.
Non-response to repeated requests for anyone on the other side of
this to define the term "phase". How can you talk about it, yet
not one of you can define it?

As to your question, IDK why you're asking. My answer is clear
and has been discused at length. The answer is Yes. The author
of the engineering paper presented at the IEEE conference of power
engineers agrees. As do the several white papers/app notes from
electrical eqpt manufacturers, etc. that I've cited as well.

In article om,
bud-- writes:
On 12/3/2013 8:25 AM, wrote:

And I'm still waiting for an answer why a system with
two phases that differ by 90 deg is acknowledged by everyone to have two
phases. If they differ by 240 deg, that's two phase right? If they
differ by 170 deg, that must be two phases, right? So, what magically
happens when they differ by 180 deg that suddenly there are no longer two
phases? And how do the electrons know?

For a garden variety split-phase supply (240/120V from a transformer
with a centertap) are there 2 "phases"?

In maths/physics, you have two phases with a mathematical
relationship of -x (or a 180 deg phase shift).

In electrical distribution, two-phase is a specific jargon term
which means something else.

There's no one right answer - it depends on the context of the
discussion.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Tue, 3 Dec 2013 07:03:58 +0100, nestork
wrote:


;3159500 Wrote:

You do sin/cos/tan functions by hand? ;-)


I can't remember whether my old Hughes Owens slide rule had trig
functions on it or not. It seems to me that it didn't.

My Versalog did. My HP45 did, too. ;-)

Back before there were calculators, engineers would carry around a book
called the CRC Handbook, published by the Chemical Rubber Company,
whoever that was.

The Chemical Rubber Company, of course. ;-)

That book had tables for squares, square roots,
cubes, cube roots, trig functions, hyperbolic trig fuctions, etc. You
would use those tables to find the values of trig functions if you knew
the angle expressed in degrees or radians.

No, most people who needed such things carried a slipstick. The tables
were needed only in the *very* few cases where extreme accuracy was
needed. The damned CRC Handbook must have weighed 5 pounds. No one
"carried it around".

No one ever worked out trig functions by hand, although you could do it.
There were Taylor series solutions developed for all the trig
functions, and the computers of the time used those series
approximations to generate sine, cosine, and tangent. For example, the
Taylor series for exponential of x, sine of x and cosine of x a

exp(x) = 1 + x + x2/2! + x3/3! + x4/4! + ...

sin(x) = x - x3/3! + x5/5! - x7/7! + x9/9! - ...

cos(x) = 1 - x2/2! + x4/4! - x6/6! + x8/8! - ...

where x3 means x cubed, or X times X times X, and the exclamation mark
means "factorial". for example: 8! = 8 X 7 X 6 X 5 X 4 X 3 X 2 X 1 =
40320

So, you can do trig functions by hand, but the way you do them lends
itself better to computer calculation.

No ****?

On Tue, 03 Dec 2013 05:04:51 -0500, ralph wrote:

On 12/03/2013 01:03 AM, wrote:
On Monday, December 2, 2013 8:29:20 PM UTC-5, Edwin wrote:
On Mon, 02 Dec 2013 15:50:47 -0800, wrote:

I say

two. And if it they agree that it is indeed still two, then it

is in fact electrically identical to split-phase 240/120V service,

so you have two phases there too.



QED





All you are doing is reversing the leads on your scope to get a fake second phase.



Your cheap trick will only fool an imbecile.

Complete inability to address the simple and carefully outlined learning excercise I gave, noted. Inability to even define the term "phase", as requested noted. As is the name calling which is what you're left with
when you don't have engineering or the facts on your side. And for the
record, a scope wasn't even involved.


I need a new furnace. Are two phase furnaces more efficient and where can I get one?

You want an oil furnace. The furnace changes the oil form the liquid
to the gaseous phase. I suppose you could use a boiler, too, but
that's not a "furnace". ;-)

wrote in message
...
I can't remember whether my old Hughes Owens slide rule had trig
functions on it or not. It seems to me that it didn't.

My Versalog did. My HP45 did, too. ;-)

Back before there were calculators, engineers would carry around a book
called the CRC Handbook, published by the Chemical Rubber Company,
whoever that was.

The Chemical Rubber Company, of course. ;-)

That book had tables for squares, square roots,
cubes, cube roots, trig functions, hyperbolic trig fuctions, etc. You
would use those tables to find the values of trig functions if you knew
the angle expressed in degrees or radians.

No, most people who needed such things carried a slipstick. The tables
were needed only in the *very* few cases where extreme accuracy was
needed. The damned CRC Handbook must have weighed 5 pounds. No one
"carried it around".


A cheap slide rule I have has the sin and tangant trig functions on it. The
wider the rule, usually the more functions on it.

I had a CRC book but it was not a 5 pounder. Just small text book size.
Not sure if it was the whole book or just a book with part of the CRC book
in it.

I remember seeing some films with a room full of engineeers with slide rules
that were shown as desiging the SR71 Blackbird.

Did you know that the SR71 Blackbird was originally intended to be called the RS71 Blackbird. But, when President Johnson (I think it was) held a briefing to explain the project to some Senators that controlled the purse strings on black projects, he repeatedly called it the SR71 instead of the RS71.

So, they quickly changed the name of the plane from RS71 to SR71.

On 12/3/2013 11:58 AM, Andrew Gabriel wrote:
In raweb.com,
writes:
On 12/3/2013 8:25 AM, wrote:

And I'm still waiting for an answer why a system with
two phases that differ by 90 deg is acknowledged by everyone to have two
phases. If they differ by 240 deg, that's two phase right? If they
differ by 170 deg, that must be two phases, right? So, what magically
happens when they differ by 180 deg that suddenly there are no longer two
phases? And how do the electrons know?

For a garden variety split-phase supply (240/120V from a transformer
with a centertap) are there 2 "phases"?

In maths/physics, you have two phases with a mathematical
relationship of -x (or a 180 deg phase shift).

In electrical distribution, two-phase is a specific jargon term
which means something else.

There's no one right answer - it depends on the context of the
discussion.


The context is, specifically, in US power distribution is a split-phase
supply called 2 phase with a phase A and phase B.

(Not "2-phase", which as you say is rather different.)

I don't think you have much split-phase over the pond. If I remember
right, construction sites may have 120/60V circuits.

On 12/03/2013 04:04 AM, ralph wrote:


I need a new furnace. Are two phase furnaces more efficient and where
can I get one?


I have a gas furnace. Can you get 2-phase gas?

On 12/03/2013 11:07 AM, bud-- wrote:

For a garden variety split-phase supply (240/120V from a transformer
with a centertap) are there 2 "phases"?

Only when the centertap is your reference point.

Maybe a 240V-only appliance (no neutral) is adding to the confusion?

I've seen a cable that gets 120V/240V form two small generators (which
each produce only 120V). Do you think that makes a difference in how
many phases you have?

On 12/3/2013 11:27 AM, wrote:
On Tuesday, December 3, 2013 12:07:05 PM UTC-5, bud-- wrote:
On 12/3/2013 8:25 AM, wrote:



And I'm still waiting for an answer why a system with

two phases that differ by 90 deg is acknowledged by everyone to have two

phases. If they differ by 240 deg, that's two phase right? If they

differ by 170 deg, that must be two phases, right? So, what magically

happens when they differ by 180 deg that suddenly there are no longer two

phases? And how do the electrons know?

For a garden variety split-phase supply (240/120V from a transformer
with a centertap) are there 2 "phases"?

The author
of the engineering paper presented at the IEEE conference of power
engineers agrees.

As previously posted, in the second half of the abstract the author
suggests a _change_ from the standard practice and wants to call
split-phase 2 phase. No vote on his suggestion is recorded. In the first
half the author says the standard practice is to call split-phase
single-phase.

The abstract does not agree with you.

On 12/03/2013 12:36 PM, wrote:

[snip]

You want an oil furnace. The furnace changes the oil form the liquid
to the gaseous phase. I suppose you could use a boiler, too, but
that's not a "furnace". ;-)


I seem to remember the state of matter being called "phase". So you have
two phase oil (liquid / gas).

--
22 days until The winter celebration (Wednesday December 25, 2013 12:00
AM for 1 day).

Mark Lloyd
http://notstupid.us

"Remember, atheism is not a worldview itself. Atheism is defined by the
view it does not have-- theism." Doug Krueger, "That Colossal Wreck"

"nestork" wrote in message
...
Did you know that the SR71 Blackbird was originally intended to be
called the RS71 Blackbird. But, when President Johnson (I think it was)
held a briefing to explain the project to some Senators that controlled
the purse strings on black projects, he repeatedly called it the SR71
instead of the RS71.

So, they quickly changed the name of the plane from RS71 to SR71.


Did not know that.

I was thinking it started out to be a fighter but there was a sudden need
for the spy plane when the U2 was shot down.

In article om,
bud-- writes:
The context is, specifically, in US power distribution is a split-phase
supply called 2 phase with a phase A and phase B.

(Not "2-phase", which as you say is rather different.)

I don't think you have much split-phase over the pond.

No. 240/480V was only used on farms in very remote areas,
and there were probably no new installations of this type
since WWII (and there maybe none left by now, having all
been upgraded to 3-phase).

It's not necessary elsewhere here because we run 230V 3-phase
down each street, so houses which need more than 1 phase get
a 3-phase 230/400V supply. (In reality, it's 240/415V for
historical reasons.)

That doesn't work with the US 120/240V, because, to a first
approximation, you can only carry it a quarter of the distance
before the voltage regulation goes too bad (and the low power
pole mount transformers actually make this much worse).
This means you have to carry the high voltage supply down
each street and use regularly spaced pole transformers to
generate the 120/240V supplies. To keep costs down, there's
usually only 1 of the 3 phases from the HV supply carried
down each street, so you don't generally have access to a
3-phase supply in any one residential street.

If I remember right, construction sites may have 120/60V circuits.

Construction sites here use a safety supply of 110V with
earthed centre-tap, i.e. 55-0-55 for single phase and 65/110V
for 3-phase, but the 0V connection is only grounded at the
transformer and carried to tools as a protective ground
conductor, and never used as a power conductor, so these
are never described as 55-0-55 or 65/110V supplies, because
there's no neutral connection. This is designed to prevent
electrocution of construction workers if a tool gets dropped
into a puddle or the cord is damaged or something similar,
as the highest voltage to ground is only 55 or 65V.

This safety supply used to be mandatory on UK construction
sites. It's no longer mandatory (that would be contrary to
EU rules on movement of workers and products), but it's what
you'll still find on all UK construction sites.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article om,
bud-- wrote:

On 12/3/2013 8:25 AM, wrote:

And I'm still waiting for an answer why a system with
two phases that differ by 90 deg is acknowledged by everyone to have two
phases. If they differ by 240 deg, that's two phase right? If they
differ by 170 deg, that must be two phases, right? So, what magically
happens when they differ by 180 deg that suddenly there are no longer two
phases? And how do the electrons know?


For a garden variety split-phase supply (240/120V from a transformer
with a centertap) are there 2 "phases"?

The above post and other replies indicate that knowledge is more
important than jargon. In terms of poly phase jargon, think of a
symmetrical 4-phase system with neutral. What we call 2-phase really is
a subsystem of two adjacent phases. Two opposite phases give you an
Edison system. You can get other such combinations.

In principle, as long as you have at least two phases other than
completely in-phase (three or four wires) or completely out of phase,
you can use transformer combinations to give you any phase combination
you like. The Scott T-connection happens to be the one that converts
between 3-phase and 2-phase (adjacent phases of a 4-phase) system.

--

Sam

Conservatives are against Darwinism but for natural selection.
Liberals are for Darwinism but totally against any selection.

On Tue, 3 Dec 2013 22:36:50 +0000 (UTC),
(Andrew Gabriel) wrote:

In article om,
bud-- writes:
The context is, specifically, in US power distribution is a split-phase
supply called 2 phase with a phase A and phase B.

(Not "2-phase", which as you say is rather different.)

I don't think you have much split-phase over the pond.

No. 240/480V was only used on farms in very remote areas,
and there were probably no new installations of this type
since WWII (and there maybe none left by now, having all
been upgraded to 3-phase).

It's not necessary elsewhere here because we run 230V 3-phase
down each street, so houses which need more than 1 phase get
a 3-phase 230/400V supply. (In reality, it's 240/415V for
historical reasons.)

We run 3-phase down most streets, too. In many places, each house has
its own transformer. Three-phase makes distribution simpler but
split-phase gives the flexibility that you have, using more than one
phase, in a simpler manner.

That doesn't work with the US 120/240V, because, to a first
approximation, you can only carry it a quarter of the distance
before the voltage regulation goes too bad (and the low power
pole mount transformers actually make this much worse).

Irrelevant.

This means you have to carry the high voltage supply down
each street and use regularly spaced pole transformers to
generate the 120/240V supplies. To keep costs down, there's
usually only 1 of the 3 phases from the HV supply carried
down each street, so you don't generally have access to a
3-phase supply in any one residential street.

Wrong. Except in rural areas, the 3-phase HV *is* distributed on each
street with, at most, a few houses on each transformer. In rural
areas they may only have one phase on the pole but there is a
transformer there, too.

On Tue, 3 Dec 2013 14:11:13 -0500, "Ralph Mowery"
wrote:


wrote in message
.. .
I can't remember whether my old Hughes Owens slide rule had trig
functions on it or not. It seems to me that it didn't.

My Versalog did. My HP45 did, too. ;-)

Back before there were calculators, engineers would carry around a book
called the CRC Handbook, published by the Chemical Rubber Company,
whoever that was.

The Chemical Rubber Company, of course. ;-)

That book had tables for squares, square roots,
cubes, cube roots, trig functions, hyperbolic trig fuctions, etc. You
would use those tables to find the values of trig functions if you knew
the angle expressed in degrees or radians.

No, most people who needed such things carried a slipstick. The tables
were needed only in the *very* few cases where extreme accuracy was
needed. The damned CRC Handbook must have weighed 5 pounds. No one
"carried it around".


A cheap slide rule I have has the sin and tangant trig functions on it. The
wider the rule, usually the more functions on it.

The only scales a slide rule needs are the 'C' and 'D' scales. The
rest are optional and included based on the target market. ...sorta
like calculators.

I had a CRC book but it was not a 5 pounder. Just small text book size.
Not sure if it was the whole book or just a book with part of the CRC book
in it.

That must have been an abridged version. The full handbook is about
the size of three encyclopedia volumes.

I remember seeing some films with a room full of engineeers with slide rules
that were shown as desiging the SR71 Blackbird.

Sure. Three significant digits is good enough for 99% of the
engineering tasks out there. Two probably covers it.

On Tue, 3 Dec 2013 17:00:31 -0500, "Ralph Mowery"
wrote:


"nestork" wrote in message
...
Did you know that the SR71 Blackbird was originally intended to be
called the RS71 Blackbird. But, when President Johnson (I think it was)
held a briefing to explain the project to some Senators that controlled
the purse strings on black projects, he repeatedly called it the SR71
instead of the RS71.

So, they quickly changed the name of the plane from RS71 to SR71.


Did not know that.

I was thinking it started out to be a fighter but there was a sudden need
for the spy plane when the U2 was shot down.

Right you are. It came from a design for an interceptor, the YF12.
The original plane was intended to shoot down Soviet bombers.
Ballistic missiles shot those plans down.

On Tue, 03 Dec 2013 14:10:34 -0600, Mark Lloyd
wrote:

On 12/03/2013 12:36 PM, wrote:

[snip]

You want an oil furnace. The furnace changes the oil form the liquid
to the gaseous phase. I suppose you could use a boiler, too, but
that's not a "furnace". ;-)


I seem to remember the state of matter being called "phase". So you have
two phase oil (liquid / gas).

No, it's the liquid phase going into the furnace and the gaseous phase
coming out. The furnace is a "phase converter". Coal and wood burners
are the same deal.

Though you have a point. Perhaps an LP fired furnace is a better
example.

On Tue, 03 Dec 2013 14:00:58 -0600, sam E
wrote:

On 12/03/2013 04:04 AM, ralph wrote:


I need a new furnace. Are two phase furnaces more efficient and where
can I get one?


I have a gas furnace. Can you get 2-phase gas?

Propane furnaces use both liquid and a gas propane.

On 12/2/13 7:24 PM, wrote:
On Mon, 02 Dec 2013 17:05:15 -0600, Dean Hoffman
" wrote:

Suppose you wanted to run an irrigation system that requires three
phase, 480 to operate. Suppose the local rural power company could only
supply you with single phase 480. Suppose Emma Genius then built a
rotary phase converter to make that three phase load run from single
phase.
Suppose that rotary phase converter created only the third leg of
the three phase to operate the three phase load. Where did the other
two necessary phases originate to operate that three phase load?

It's quite simple. The rotary phase converter is a generator.

But doesn't a phase converter manufacture just the third phase?
So how would three phase motors run off of it if single phase is
actually just one phase? There must actually be two incoming phases.
That's why it makes sense to me that the term single phase is a
misnomer at least on the secondary side of the utility transformer.
Other misnomers if you're really bored:
http://preview.tinyurl.com/ls5yz56

On Tue, 03 Dec 2013 20:18:29 -0600, Dean Hoffman
" wrote:

On 12/2/13 7:24 PM, wrote:
On Mon, 02 Dec 2013 17:05:15 -0600, Dean Hoffman
" wrote:

Suppose you wanted to run an irrigation system that requires three
phase, 480 to operate. Suppose the local rural power company could only
supply you with single phase 480. Suppose Emma Genius then built a
rotary phase converter to make that three phase load run from single
phase.
Suppose that rotary phase converter created only the third leg of
the three phase to operate the three phase load. Where did the other
two necessary phases originate to operate that three phase load?

It's quite simple. The rotary phase converter is a generator.

But doesn't a phase converter manufacture just the third phase?

Depending on how you look at it. In any case, how do you think it
"manufactures" that third phase. The induction motor becomes a
motor-generator.

So how would three phase motors run off of it if single phase is
actually just one phase? There must actually be two incoming phases.

Nope. Only one.

That's why it makes sense to me that the term single phase is a
misnomer at least on the secondary side of the utility transformer.

Words mean things. You're wrong.

Other misnomers if you're really bored:
http://preview.tinyurl.com/ls5yz56

Except "single phase" is *not* a misnomer.

" wrote:
I can define it. And I'm still waiting for an answer why a system with
two phases that differ by 90 deg is acknowledged by everyone to have two
phases. If they differ by 240 deg, that's two phase right? If they
differ by 170 deg, that must be two phases, right? So, what magically
happens when they differ by 180 deg that suddenly there are no longer two
phases? And how do the electrons know?

You are in fact exactly correct.

If you have three distinct conductors that are not connected to
each other, it is defined as a 2 phase system.

Between any two conductors there is just one phase. Hence if
any one of the three conductors is labeled as "Neutral", the
other two are Phase 1 and Phase 2. (If there are 40 conductors,
there are 39 phases.)

The magic about 180 degree phase shift is not really magic. No
matter what the phase relationship is, there is a single phase
between any two conductors. Of course with a two phase system
the voltage between the two non-neutral conductors will be
greatest if the phase relationships to neutral are 180 degrees
different. It will be minimum of course if the phase
relationships are 0 degrees.

The same significance for a three phase system occurs of course
with 120 degree phase relationships.

--
Floyd L. Davidson http://www.apaflo.com/
Ukpeagvik (Barrow, Alaska)

On Tuesday, December 3, 2013 2:57:16 PM UTC-5, bud-- wrote:
On 12/3/2013 11:58 AM, Andrew Gabriel wrote:

In raweb.com,

writes:

On 12/3/2013 8:25 AM, wrote:



And I'm still waiting for an answer why a system with

two phases that differ by 90 deg is acknowledged by everyone to have two

phases. If they differ by 240 deg, that's two phase right? If they

differ by 170 deg, that must be two phases, right? So, what magically

happens when they differ by 180 deg that suddenly there are no longer two

phases? And how do the electrons know?



For a garden variety split-phase supply (240/120V from a transformer

with a centertap) are there 2 "phases"?



In maths/physics, you have two phases with a mathematical

relationship of -x (or a 180 deg phase shift).



In electrical distribution, two-phase is a specific jargon term

which means something else.



There's no one right answer - it depends on the context of the

discussion.





The context is, specifically, in US power distribution is a split-phase

supply called 2 phase with a phase A and phase B.



No, that is most certainly *not* what the discussion was ever about.
I never said it was commonly called two phase. No one else ever said it
was called that either. Like the IEEE engineer that delivered the paper
at the power engineering conference, I simply said that in fact from
an electrical engineering perspective, there
are two phases present. The references I've cited from electrical
eqpt manufacturers, etc, say the same thing. They explicitly talk
about two phases being present. Are they all nuts too?

I'd also point out that this whole thing started when a poster pointed
out that one hot on a split-phase service is 180 deg out of phase with
the other. That is what krw said was wrong, that they are not 180
deg out of phase, they are "opposites". That is about as dumb a thing
as one can imagine. I've given probably 10 references now, including
about as credible a refernce as you can get, a paper delivered at an IEEE conference of power engineers, where the author/speaker, says there is a 180 deg phase relationship, that you do have two phases. He's the author
of a whole bunch of very technical papers on power engineering, all
published by the IEEE, a peer reviewed group. Is he and the IEEE nuts too?

http://ieeexplore.ieee.org/xpl/artic...number=4520128

"Which now brings into focus the reality that standard 120/240 secondary systems are not single phase line to ground systems, instead they are three wire systems with two phases and one ground wires. Further, the standard 120/240 secondary is different from the two phase primary system in that the secondary phases are separated by 180 degrees instead of three phases separated by 120 degrees."

http://www.samlexamerica.com/support...Circuit s.pdf

Page 2: Explicitly talks about split-phase consisteing of two phases,
A and B and that they are 180 deg opposite each other.

http://www.behlman.com/applications/AC%20basics.pdf

Says the same thing.

And I'd also note that none of those references say it's called
two phase either. Just that there are in fact two phases present.


It's properly called "split-phase", everyone agrees on that. When you split
something, can you give us an example of a case where you still have
just one of those things? In quantum physics I guess, but not in the
everyday world. The argument that because it's commonly referred to
as single phase doesn't change what's there. It's like saying that
because you call something Kleenex, it's not also correct that when
you analyze it, it's a soft paper tissue. Or that because water is
called water, when you correctly analyze it, it's not H20, made up
of hydrogen and oxygen. From the power company's perspective, split-phase
originates from one of their 3 primary phases. So, I'm guessing, that
is the historical reason that it's frequently just called single phase
service, to distinguish it from the other common power source, 3 phase.

And I'm still waiting for someone on the other side of this to provide
their definition of the engineering term "phase". How can people make
post after post, yet no one can define a very basic term? Good grief.
Or to address the simple excercise in phase, where I go from what
you all say is a true two phase service to split-phase, just by changing
the phase difference? Split-phase either has two phases
present, or else something magical happens at 180 deg, as you slowly
change the phase from 90, to 120, to 179, to finally 180. How can
there be two phases at every other possible phase angle, but not at 180?

On Tuesday, December 3, 2013 3:06:36 PM UTC-5, sam E wrote:
On 12/03/2013 11:07 AM, bud-- wrote:



For a garden variety split-phase supply (240/120V from a transformer

with a centertap) are there 2 "phases"?



Only when the centertap is your reference point.



You mean the centertap that is tied to the neutral
and earthed? The zero potential point for all 120V loads?
THAT reference point? It's the most logical reference point
when analyzing the system in question. It's not like someone
is talking about using Mars as a system reference point.



Maybe a 240V-only appliance (no neutral) is adding to the confusion?



No confusion here.



I've seen a cable that gets 120V/240V form two small generators (which

each produce only 120V). Do you think that makes a difference in how

many phases you have?

Not much to go on there. But depending on the number of conductors,
and how it's tied together, if at all, whether the generators are running in
synch or not, then sure it makes a big difference in how many phases are
present.

On Tuesday, December 3, 2013 9:23:35 PM UTC-5, wrote:
On Tue, 03 Dec 2013 20:18:29 -0600, Dean Hoffman

" wrote:



On 12/2/13 7:24 PM, wrote:

On Mon, 02 Dec 2013 17:05:15 -0600, Dean Hoffman

" wrote:



Suppose you wanted to run an irrigation system that requires three

phase, 480 to operate. Suppose the local rural power company could only

supply you with single phase 480. Suppose Emma Genius then built a

rotary phase converter to make that three phase load run from single

phase.

Suppose that rotary phase converter created only the third leg of

the three phase to operate the three phase load. Where did the other

two necessary phases originate to operate that three phase load?



It's quite simple. The rotary phase converter is a generator.



But doesn't a phase converter manufacture just the third phase?



Depending on how you look at it. In any case, how do you think it

"manufactures" that third phase. The induction motor becomes a

motor-generator.



So how would three phase motors run off of it if single phase is

actually just one phase? There must actually be two incoming phases.



Nope. Only one.



That's why it makes sense to me that the term single phase is a

misnomer at least on the secondary side of the utility transformer.



Words mean things. You're wrong.



Other misnomers if you're really bored:

http://preview.tinyurl.com/ls5yz56



Except "single phase" is *not* a misnomer.

The IEEE says you're wrong. From an IEEE paper delivered at a
conference of power engineers and published by the IEEE. It directly
addresses the specific issue:

http://ieeexplore.ieee.org/xpl/artic...number=4520128

"Which now brings into focus the reality that standard 120/240 secondary systems are not single phase line to ground systems, instead they are three wire systems with two phases and one ground wires. Further, the standard 120/240 secondary is different from the two phase primary system in that the secondary phases are separated by 180 degrees instead of three phases separated by 120 degrees. "


Check out the author's credentials, all the highly technical papers he's
had published by the IEEE.

Your response..... crickets and name calling.


Still waiting for your answer to the simple question asked a dozen
times now. What is your definition of the electrical engineering term
"phase"? How can you keep posting about something, yet you can't
even define it?

Still waiting for an answer to the simple exercise I presented. We
have what I believe you acknowledge is a two phase system used to
deliver power in the past. It had two phases and a neutral. One phase
was 90 deg off from the other. That had two phases, right?

OK, so now I change the phase relationship so they differ by 120 deg.
How many phases now? Still two? I make it 220 deg. Still two?
I make it 175 deg. Still two? I make them differ by 180, how many
phases do I have now? And if the latter is still two phase, it's
electrically indistinguishable from what you have on a 240/120V
split phase service.

All simple questions, that even a high school student could answer,
but we have no answers, just crickets and insults.

On Wed, 4 Dec 2013 01:17:57 -0800 (PST), "
wrote:

On Tuesday, December 3, 2013 9:23:35 PM UTC-5, wrote:
On Tue, 03 Dec 2013 20:18:29 -0600, Dean Hoffman

" wrote:



On 12/2/13 7:24 PM, wrote:

On Mon, 02 Dec 2013 17:05:15 -0600, Dean Hoffman

" wrote:



Suppose you wanted to run an irrigation system that requires three

phase, 480 to operate. Suppose the local rural power company could only

supply you with single phase 480. Suppose Emma Genius then built a

rotary phase converter to make that three phase load run from single

phase.

Suppose that rotary phase converter created only the third leg of

the three phase to operate the three phase load. Where did the other

two necessary phases originate to operate that three phase load?



It's quite simple. The rotary phase converter is a generator.



But doesn't a phase converter manufacture just the third phase?



Depending on how you look at it. In any case, how do you think it

"manufactures" that third phase. The induction motor becomes a

motor-generator.



So how would three phase motors run off of it if single phase is

actually just one phase? There must actually be two incoming phases.



Nope. Only one.



That's why it makes sense to me that the term single phase is a

misnomer at least on the secondary side of the utility transformer.



Words mean things. You're wrong.



Other misnomers if you're really bored:

http://preview.tinyurl.com/ls5yz56



Except "single phase" is *not* a misnomer.

The IEEE says you're wrong. From an IEEE paper delivered at a
conference of power engineers and published by the IEEE. It directly
addresses the specific issue:

You keep proving that you're illiterate. You really are getting as bad
as Malformed.

snipped more drivel, unread

On 12/3/2013 4:36 PM, Andrew Gabriel wrote:
In raweb.com,
writes:
The context is, specifically, in US power distribution is a split-phase
supply called 2 phase with a phase A and phase B.

(Not "2-phase", which as you say is rather different.)

If I remember right, construction sites may have 120/60V circuits.

Construction sites here use a safety supply of 110V with
earthed centre-tap, i.e. 55-0-55 for single phase and 65/110V
for 3-phase, but the 0V connection is only grounded at the
transformer and carried to tools as a protective ground
conductor, and never used as a power conductor, so these
are never described as 55-0-55 or 65/110V supplies, because
there's no neutral connection. This is designed to prevent
electrocution of construction workers if a tool gets dropped
into a puddle or the cord is damaged or something similar,
as the highest voltage to ground is only 55 or 65V.

It is what I attempted to convey it too few words.

If I remember right, there are bathroom outlets that are connected the same.


This safety supply used to be mandatory on UK construction
sites. It's no longer mandatory (that would be contrary to
EU rules on movement of workers and products), but it's what
you'll still find on all UK construction sites.


How does the EU get involved.