Stupid question of the day....

[TokaMundo]

Yes, and it has a surface area function, retard boy.

Got some numbers?

Your IQ is ten.

Or is this going to be another one of your
unsubstantiated claims?

Just as I stated, when the wire turns cherry red from current, it is
uniformly heated.


The entire wire has the same temp and the same heat. The only
exception is the connection points to the current source.

I never said it did. I said the current generates the heat, and
then corrected to say that the resistance to said flow is the
condition which causes the generated. I didn't say a damned thing
about the current generating the resistance. That is a function of
the media the current is passing through.

Your remark is retarded.

The wire's resistance

No shit. That's what "resistance to said flow" refers to, dipshit.

and its
temperature coefficient of resistance are due to the resistivity and
tempco of the material the wire is made of.

No shit.

What you have to say about it is certainly immaterial.

The phenomenon occurs with
or without your permission.

The phenomenon of the entire wire being at the same temperature.

You have no point. You and your stupidity has been exiled to the
pointless forest.

Got some numbers, or is that just some more of your bullshit
opinion?

Got something that proves otherwise? Otherwise your rebuttal is
nothing more than bullshit opinion.

 

[TokaMundo]

I thought large diameter conductors in switchyards were for corona
reduction.

Large diameter turns (changes in direction) are. It is very bad to
make a sharp turn on a wire carrying HV as the field gradient at the
turn is high. Large radius turns are used to keep such gradients low.

Larger wire diameters also keep it lower. Look at an ionizer wire
in larger air purification systems. They use a very thin gauge wire
specifically because it will have a have gradient, and closely
resemble a point along its entire length.

I would say that the material the wire is made of would make a
difference, and change that figure accordingly so such an arbitrary
number is pretty fucking vague.

Since TokaMundo is infallable,

Your an insulting bastard. Feel better now?

consider the possibiltiy that he is
actually the pope.

You're also a retarded bastard as well.

He has also been identified as a troll.

By John, the troll, and his minions. Are you one of them, asswipe?

 

[TokaMundo]

What is a high frequency?
If this is not defined in the source, then most of the time a high frequency
will be any frequency on what the voltage on the line cannot be taken equal
at every place of the line because of linelength and wavelength.

The voltage on the line is different along its length for plenty of
reasons, the least of which is skin effect.

By this 60Hz can be a very high frequency if you have a cable of several
kilometers.

A mile run at DC, and one at 60Hz won't yield significantly
different losses. If the voltage is high enough the drop will be even
less significant.

 

[TokaMundo]

Someone once tolf me something, I believe it wass: "Don't feed the trolls",
it seems to me that they are having a ball with food in abundance.

Just don't ever try to exclude yourself from the fray, because you
are just as deep in the shit as the next guy.

 

[John Fields]

Your a fucking kingpin when it comes to being retarded.

^^^^
Tsk, tsk, tsk...

Geez, Tokey, I'm not the one making all the spelling, punctuation,
and grammar misteaks. Oh, that one was just for fun.

 

[John Fields]

Gee, someone must've received a bad grade last year in
their freshman circuit analysis class...

 

[John Fields]

Just as I stated, when the wire turns cherry red from current, it is
uniformly heated.

---
Sorry, Charlie, there'll still be a temperature gradient across the
diameter of the wire. There has to be, since the surface of the
wire will be radiating heat and being cooled by convection.
---

The entire wire has the same temp and the same heat. The only
exception is the connection points to the current source.

---
Nope. I'm sorry that you can't understand why the gradient _has_ to
be there, but it does, trust me. Or not, but continue on your
present course and all you'll do is further convince everyone that
you're as pig-headed now as you ever were.
---

I never said it did.

---
Sure you did. If you go back and read the sentence more carefully,
what you said was:

"and it is that current which generates the heat, or more precisely,
the resistance to said current flow."

Now, if we restructure the sentence in accordance with your
instructions about preciseness, it reads:

"and it is that current which generates the resistance to said
current flow."

which is incorrect.

What you have to say about it is certainly immaterial.


The phenomenon of the entire wire being at the same temperature.

---
The only way there would be no resistance variation across the
diameter of the wire would be if there was no charge flowing through
the wire and it was in an isothermal environment. Period. End of
discussion.
---

You have no point. You and your stupidity has been exiled to the
pointless forest.

---
You always regress to your fourth grade insults when you don't have
a leg to stand on and all you want to do is make noise, huh?
---

Got something that proves otherwise?

---
Sure, but you wouldn't understand it. Even if you did, you'd still
continue with your harangue in order to keep from having to admit
ignorance like you always do.
---

Otherwise your rebuttal is nothing more than bullshit opinion.

---
You've got the cart before the horse.

I hypothesized that there was a temperature gradient in a current
carrying conductor, originally, in a reply to one of John Larkin's
posts about skin depth.

That concept was elaborated on by daestrom, and then rebutted by
you, so unless you can prove that you're right and I'm wrong, my
hypothesis stands and the rebuttal, which _you_ made, is nothing
more than bullshit opinion.

 

[John Fields]

I would say that the material the wire is made of would make a
difference, and change that figure accordingly so such an arbitrary
number is pretty fucking vague.

---
Since very little of what you say is true, a reference would be
preferable to an opinion.

Something like this:

http://en.wikipedia.org/wiki/Skin_effect
could even help you to _prove_ your point.

 

[Michael A. Terrell]

I think "Sediment" would be a better description for TokaMundo,
John. At least that's the sound he made when he was tossed in my troll
bucket weeks ago.

--
Link to my "Computers for disabled Veterans" project website deleted
after threats were telephoned to my church.

Michael A. Terrell
Central Florida

 

[Don Kelly]

The table I saw shows the AC and DC resistance as being exactly the
same for both.

Your flaw is where you failed to note the topic given in the CRC
handbook.

60 Hz is NOT high frequency... at all.

Try some calculations at 100 kHz and you'll see that those
frequencies down near zero (ie 60Hz) yield very nearly nil difference.

---------------------
In Engineering Electromagnetics, Hayt points out that in a power station a
bus bar for alternating current at 60 Hz much more than 1/3rd of an inch (8
mm) thick is wasteful of copper, and in practice bus bars for heavy AC
current are rarely more than 1/2 inch (12 mm) thick except for mechanical
reasons.
This seems to imply that the bulk of the current is in the outermost 4mm.




This does not mean that conductors, at 60 Hz, which are less than 8mm in
diameter do not show skin effect. 60 Hz AC resistance/DC resistance for
commonly used conductors (say 12 to 6 gauge) may be 1.1 to 1.25 in practice-
this includes skin and proximity effects . However, anyone wanting to do
the math from scratch better be familiar with Bessel functions. Are you?


Skin effect, per se, is not a concern with ACSR power cables as there are a
number of other factors which are more important.

Possibly the approximations for high frequencies are not valid at 60Hz but
this does not mean that skin effect is negligable- except for conductors 000
or higher - provided they are straight. .
The point is that there is no hard and fast "rule" covering all situations

 

[DBLEXPOSURE]

---------------------
In Engineering Electromagnetics, Hayt points out that in a power station a
bus bar for alternating current at 60 Hz much more than 1/3rd of an inch
(8 mm) thick is wasteful of copper, and in practice bus bars for heavy AC
current are rarely more than 1/2 inch (12 mm) thick except for mechanical
reasons.
This seems to imply that the bulk of the current is in the outermost 4mm.




This does not mean that conductors, at 60 Hz, which are less than 8mm in
diameter do not show skin effect. 60 Hz AC resistance/DC resistance for
commonly used conductors (say 12 to 6 gauge) may be 1.1 to 1.25 in
practice- this includes skin and proximity effects . However, anyone
wanting to do the math from scratch better be familiar with Bessel
functions. Are you?


Skin effect, per se, is not a concern with ACSR power cables as there are
a number of other factors which are more important.

Possibly the approximations for high frequencies are not valid at 60Hz but
this does not mean that skin effect is negligable- except for conductors
000 or higher - provided they are straight. .
The point is that there is no hard and fast "rule" covering all situations

Thanks Don!

I have been watching this thread for days. I like your answer. It's
allways give and take, no hard and fast rules that fit every situation.
And even better yet, You made your point without slamming anybody..

Well Done, Hats off....

 

[Don Kelly]

No shit.

For one thing, they are primarily designed for high tensile strength
as they have to stay mounted through all weather and environmental
conditions.

After that, their resistance is an issue as the primary material has
to be steel for the tensile forces involved. They usually get clad in
Aluminum as copper is too costly for such long runs, and the losses in
using aluminum are little in comparison. This is also the reason that
high voltages are used in long haul transmission lines. The loss
over 2000 feet of line with 120 volts on it is significantly different
than the loss over 2000 feet of line with 20,000 volts on it.

--------
Gee - I thought I^2R loss depended on the current, not the voltage. For a
given power you are right but you didn't state this.
-------------

Corona will become a problem as that line voltage is raised. At
that time line spacing becomes an issue.

Tower spacing is a function of the terrain being traversed. Line
spacing ON a given tower design is a function only of the voltage that
is proposed to be carried, and the total number of conductors.

Skin effect, in these high tension line realms is only an issue if
the idiots that made the wire didn't know how deep to make the
cladding. If the wire is clad to thinly, there will be more loss as
the steel is more resistive, and the wire will heat more as well.
If it is clad too thickly, an unnecessary cost is introduced.

-------
Right -and I have seen ACSR cable with an aluminum depth that exceeds 2cm.
This is unusual and now smaller conductors in bundles (spaced 30-45cm
between conductors ) because of lower inductive reactance and surface fields
that result-notghing to do with skin effect.

This is specifically because the skin depth is so deep at this
frequency, NOT due to it being a thin depth! So in power line cases,
the effect is an issue of how deep the cladding is, not how thin.

-----
Not a big deal. The usual skin depth rules go out the window because of the
magnetic core material and the fact that you have strands of aluminum in
close proximity.
---------

In RF transmission lines, which are typically nickel or silver
plated, it becomes a cost issue, and claddings are made as thin as
possible for a given application frequency. These cases are where one
will see hollow conductors, or plated tube or solids. This is where a
Litz configuration or plated conductor will assist one in design of a
circuit.

At 60Hz, a high voltage step up transformer will have some transfer
efficiency number. At switching frequencies, the same transformer
design (wire turn count wise) will operate better if the primary, and
or secondary have litz wire used in them as the effective resistance
of the winding will be reduced at the higher frequencies.

--------
Note that the equivalent of Litz wire has been used and is used in 60 Hz
generator windings. Wonder why? The individual strands are too small to have
an appreciable skin effect but there is also the proximity effect which can
be more of a problem.
-------------

 

[Don Kelly]

Skin effect has nothing to do with voltage. Nor is the 15KV level a
"boundary" . It has long been recognised that larger diameter conductors
will reduce surface fields and corona as well as reducing inductance.
However, large diameter conductors are heavy. Initially a copper "barrel
stave" conductor was used but then the idea of a steel core for strength and
aluminum for conductivity replaced this original idea. Skin effect was
reduced and was considered in ther design but basically strength without
loss of conductivity was the basis for practical large diameter conductors.
The bundling of conductors (say 2 to 4 conductors spaced 30-45cm apart) is
an extension of this - effective very large diameter and lower surface
fields and series inductance at a reasonable price and weight savings. This
has nothing to do with skin effect.

 

[TokaMundo]

---
Sorry, Charlie, there'll still be a temperature gradient across the
diameter of the wire. There has to be, since the surface of the
wire will be radiating heat and being cooled by convection.
---

If it were modeled after the earth, with the heat source in the
center, I would agree. I feel, however, that it is more closely
modeled after Io, which is heated by the magnetic forces of Jupiter,
and more closely approximates an evenly heated body.

In the wire, since the heat is generated throughout the medium via
current flow, even from low currents on up to my cherry red scenario
would show the wire at the same temp from center to outer surface.

The "thermal skin" of the wire that would be slightly cooler due to
surface convection is very thin and beneath it the medium has even
temperature, not a gradient to the center. The reason is that the
surface that you claim to be giving up so much of its heat by
convection isn't that large compared to the whole mass of the wire,
and the source of the heat is throughout the wire's medium.

That's for bare wire and for sheathed or coated wire the containment
is even better.

The word for today is emissivity.

Even though the number is high for bare, matte finished copper, it
still doesn't give up its heat fast enough to have a full gradient
throughout the wire. It would appear as a "skin" when graphed. A
very thin skin.

 

[TokaMundo]

---
Sure you did. If you go back and read the sentence more carefully,
what you said was:

"and it is that current which generates the heat, or more precisely,
the resistance to said current flow."

Now, if we restructure the sentence in accordance with your
instructions about preciseness, it reads:

"and it is that current which generates the resistance to said
current flow."

Like I said before... I never said that, you fucking asswipe.
You're nothing more than a manipulative lard ass.

which is incorrect.

Yes, you are.

 

[TokaMundo]

wrong:
http://groups.google.com/group/sci....1738a7b007dc8c?lnk=st&rnum=1#f31738a7b007dc8c

Nice.

The condensed form (in a manner of speaking) :-]


http://en.wikipedia.org/wiki/Special_relativity_for_beginners
http://www.fourmilab.ch/etexts/einstein/specrel/www/

 

[TokaMundo]

I see. Instead of reason, you prefer insult.

I will neither read your "proof" nor will I shut up, and if you
don't like it, you miserable son of a bitch, you can go ****
yourself.


John Fields
Professional Circuit Designer

THIS GUY IS THE TROLL, FOLKS!!!

 

[TokaMundo]

It is all speculation of course. I have never seen an electron, Have you?

You have never seen lightning? It is an entire stream of them, IN
MOTION. The visible effects are enough. Ever seen "Ball Lightning"?
I suppose ionized air is just the visible result of the electron
passing, and it moves so fast as not to be visible with the human eye,
so what we see is air turned plasma.

Ever had a jolt fire into you? The pain at the entry site tells one
actual movement occurs. The jolt through the body and out the exit
point also concur.

See the photo at alt.binaries.pictures.misc titled "strike"

 

[John Fields]

Like I said before... I never said that, you fucking asswipe.
You're nothing more than a manipulative lard ass.

 

[TokaMundo]

Real mature, Johnny. Ranks right up there with the ten year olds.
one of my turds has more character than you do, old man.