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Re: Can twisted wire replace shielded wire?

N

NunYa Bidness

Jan 1, 1970
0
This is not a trivial problem.

For a modern computer, it is. One needs to be a good programmer to
write a good nesting application though. Hell, it was on hercules
graphics at the time!
What methods were used? Software? With what economic
success, compared to perfect?

Oh it was a tried and true HVAC industry package. I do not recall
the name of the software as I was strictly involved with breaking down
the individual pieces into their constituent cutouts. Once that was
done, the figures for their shapes were input by me and when done, the
nesting program did the rest. A machine operator loaded the plasma
cutter, and losses were less than 55 per 4' x 8' sheet. It was nearly
always stainless.

As far as I know, there was no method used by a human that could do
the job with less losses. I am certain that nesting software has come
even farther since... it isn't all that involved.

It was a Vax/Vms desktop PC, and I think it was dated out to the mid
80's as/and the I/O module was 100 wire wrap. It used standard serial
RS-232 ports. The forms created were for HVAC. Almost always 100%
fully welded stainless as the mainstay of their business was
institutional, hospital, dust collection, jails, etc.

It was an interesting job. Well beneath my capacity, however. It
was... after all, a mere data entry position essentially.

When I brought the interface problem to their attention, I likely
saved them gobs-O-cash because their volume required that that third
machine get running. I probably stepped on some toes when I solved it
for them... a mere data entry dude. Didn't even get a pat on the
back.
 
N

NunYa Bidness

Jan 1, 1970
0
Perfect conservation ?


Conservation perfect ?


"Voltage changes which occur in a circuit as a result of energy dissipation"


John, designated bloody mary mixer
Do not forget to microwave pasteurize it before serving.
 
M

Michael A. Terrell

Jan 1, 1970
0
NunYa said:
I worked for a short time pumping figures into a VAX that "nested"
cut shapes together to minimize material losses in a sheet steel
plasma cutter setup. We had 3 machines, but the last one never
worked. It was a mere 150' feet from the VAX based machine controller
apparatus.

I noticed that the 9 conductor, foil shielded cable they used to
connect to the machine 150' away was draped directly over and snaked
around heavy power conduits that fed some of the high power machinery
being used in the shop (welders, shears, brakes, etc.).

I told them the reason their machine did not work was the routing of
that cable, as the spec for that particular serial line could traverse
much farther than a mere 150'. The noise introduced by the power
conduits was enough to keep the ports from handshaking/establishing a
connection for data transmission.

They bought a new cable, and routed it a bit better, and the machine
now functions.

This is why cable TV hard line runs are kept a minimum specific
distance away from power lines, both on the poles, and the soft coax
in the local installations.

LF fields can pass through both the conduits and the shields. Sure,
they attenuate some of it, but why ask for noise by nesting them right
next to each other.

Anyway... this proves your point.


The separation of CATV, Phone, and the secondaries on power poles is
to reduce the chance of additional damage when a line breaks, and to
provide enough room to service the line mounted equipment with
reasonable safety. If they are too close together and a line is damaged
it can short to the jacket of the CATV or telephone lines, although the
old leaded phone cables and bare aluminum CATV cable are disappearing.
 
M

Michael A. Terrell

Jan 1, 1970
0
Cliff said:
But if I stick a few in one end of a long wire a few others
want to pop out the other end quite quickly.


That's because electrons are very anti-social creatures.
 
F

Floyd L. Davidson

Jan 1, 1970
0
Michael A. Terrell said:
The separation of CATV, Phone, and the secondaries on power poles is
to reduce the chance of additional damage when a line breaks, and to
provide enough room to service the line mounted equipment with
reasonable safety. If they are too close together and a line is damaged
it can short to the jacket of the CATV or telephone lines, although the
old leaded phone cables and bare aluminum CATV cable are disappearing.

The separation does very little to avoid damage when a power
line breaks. It does avoid damage when the CATV or telco cable
breaks. None of those are common problems though. The
separation is mostly to allow 1) acess by craft people to the
CATV/telcom cables, 2) reduction of induced power line noise,
and 3) provide lightening protection to the CATV/telco cables.

(You will be *very* hard pressed to find any lead sheathed telco
cable still in service today.)
 
C

Cliff

Jan 1, 1970
0
I am certain that nesting software has come
even farther since... it isn't all that involved.

Sort of sounds like you had a special case of
rectangular/prismatic parts .... not the general
case.
 
N

NunYa Bidness

Jan 1, 1970
0
Sort of sounds like you had a special case of
rectangular/prismatic parts .... not the general
case.


No. The parts were standard HVAC reducers, elbows, etc.

So, the shapes were quite varied and more than mere rectangles.

Perhaps what I should have said is that such software has *not* come
much farther since. That makes better since, as it is likely not all
that involved.

Since I do not know, however, it is mere speculation.

I do not think the shapes were anything other than "the general
case". The only difference being that fully welded parts do not have
the same flanges, etc. at their seams, like non welded HVAC parts do.

I wasn't really there long enough to take in all that much knowledge
in the matter. I moved on to bigger and better things.

I did wonder if folks like Milacron, in the same town had such
programs running. It would only seem prudent to save material costs.
 
N

NunYa Bidness

Jan 1, 1970
0
The separation does very little to avoid damage when a power
line breaks.

Which is why also that such services will always be found BELOW
power.

CATV hard line also always has a nice, big GROUNDED "carrier strand"
from which the lines hang, as does ma bell IIRC.
It does avoid damage when the CATV or telco cable
breaks. None of those are common problems though. The
separation is mostly to allow 1) acess by craft people to the
CATV/telcom cables, 2) reduction of induced power line noise,
and 3) provide lightening protection to the CATV/telco cables.

(You will be *very* hard pressed to find any lead sheathed telco
cable still in service today.)

Once at the "service drop" level, power run avoidance is certainly
for noise minimization. Like traversing across an attic or crawl
space. We had to keep a minimum of 18" between any comm run and
power. Most such runs were horizontally spaced in post wire settings.

In a pre-wired structure, with vertically spaced runs, I am sure
spacing was for keeping AC power line noise injection to a minimum as
well. Particularly in residential structures where both power and
comm runs are not found in conduits, and "line breaks" are not very
likely at all. When they do occur, said lines do not fall onto each
other when they are supported from stud to stud to stud.

So on the poles, noise abatement/minimization *may* not be the
primary reason, but it certainly is in structures.
 
F

Floyd L. Davidson

Jan 1, 1970
0
NunYa Bidness said:
Which is why also that such services will always be found BELOW
power.

Not so. See the list of three reasons below? 1 and 3 are the
reasons to put CATV and comm cable below the power cable.
CATV hard line also always has a nice, big GROUNDED "carrier strand"
from which the lines hang, as does ma bell IIRC.

As does virtually all aerial cable. (Check out the construction
of power cable too!)
Once at the "service drop" level, power run avoidance is certainly
for noise minimization. Like traversing across an attic or crawl
space. We had to keep a minimum of 18" between any comm run and
power. Most such runs were horizontally spaced in post wire settings.

That avoidance consideration starts at the CO.
In a pre-wired structure, with vertically spaced runs, I am sure
spacing was for keeping AC power line noise injection to a minimum as
well. Particularly in residential structures where both power and
comm runs are not found in conduits, and "line breaks" are not very
likely at all. When they do occur, said lines do not fall onto each
other when they are supported from stud to stud to stud.

So on the poles, noise abatement/minimization *may* not be the
primary reason, but it certainly is in structures.

It *absolutely* is a primary concern on poles.
 
N

NunYa Bidness

Jan 1, 1970
0
It *absolutely* is a primary concern on poles.

That is what I originally stated, and the other guy refuted...
or seemed to.
 
C

Cliff

Jan 1, 1970
0
No. The parts were standard HVAC reducers, elbows, etc.

So, the shapes were quite varied and more than mere rectangles.

Perhaps what I should have said is that such software has *not* come
much farther since. That makes better since, as it is likely not all
that involved.

Since I do not know, however, it is mere speculation.

I do not think the shapes were anything other than "the general
case". The only difference being that fully welded parts do not have
the same flanges, etc. at their seams, like non welded HVAC parts do.

Still sounds like a special case. All of the parts seemed to
be composed of simple rectangular shapes (or combinations
of them - prismatic).

Optimal nesting when things like curved shapes are involved or
random numbers of odds & ends on various sheet sizes ... I seem
to recall it as a bit of a puzzle. And what sheet or strip size is
best for the parts to be made? A huge cost factor in stamping
& die design - trim waste. It's a 2D packing problem.

http://citeseer.ist.psu.edu/342654.html
http://garage.cse.msu.edu/papers/GARAGe94-4.pdf
http://www.sigmanest.com/
http://www.most2d.com/
http://www.autocode.com/cadcam.htm

Lots more if you search. How good is any of it?

I can vouch for none of it <G>.
 
N

NunYa Bidness

Jan 1, 1970
0
Still sounds like a special case. All of the parts seemed to
be composed of simple rectangular shapes (or combinations
of them - prismatic).

Optimal nesting when things like curved shapes are involved or
random numbers of odds & ends on various sheet sizes ... I seem
to recall it as a bit of a puzzle. And what sheet or strip size is
best for the parts to be made? A huge cost factor in stamping
& die design - trim waste. It's a 2D packing problem.

Of course it is a 2D problem.

There were several shapes that included curves. They were the most
"wasteful" as nesting other pieces close to them still yields lost
material.
 
J

Jasen Betts

Jan 1, 1970
0

I asked because the above specifically mentioned superconductors...
Run the LTSpice simulation below, three cases of 1000 miles of RG59-U,
terminated. shorted, and open at 1 MHz. You'll find all 3 cases look like
75 ohms. Constants are per Belden data.

I was talking DC resisitance, 1MHz is a funny kind of DC...


Bye.
Jasen
 
R

Rich Grise

Jan 1, 1970
0

You excised "for a little while".

You, sir, are demonstrating most of the characteristics of an idiot.

Good-bye.
 
J

John Scheldroup

Jan 1, 1970
0
NunYa Bidness said:
Do not forget to microwave pasteurize it before serving.

Mr. and Mrs T', or in reference to tomato juice in general ?

Bloody Mary Mix:

1 can 46 oz. tomato or clamato juice
2 Tbs. worcestershire sauce
1 Tbs. lemon juice
1 tsp. salt
1 tsp. celery salt
1 tsp. chili powder
1 tsp. tobasco or hot sauce

In picture combine all ingredients, stir and refrigerate. Serve on the rocks
with 3/4 - 1 shot vodka. Stir with a stock of celery or pickle appetizer.

John

--
http://www.berkeley.edu/news/media/releases/2004/08/16_Lanzara.shtml

Vibrations in crystal lattice play big role in high temperature superconductors
By Robert Sanders, Media Relations | 16 August 2004


http://idb.exst.jaxa.jp/ideadata/04048/199906E04048000/199906E04048000.html

Crystal Growth of Organic Superconductors Under Microgravity | 1999

Results:

1) While raising concentration of the donor and acceptor materials to
satisfactory levels on earth required approximately three months, the same
concentrations were achieved in approximately seven days in orbit. The organic
superconducting single crystals grown under microgravity were of similar size
to those grown on earth, while being of higher quality.

2) On earth, crystals grew not only in the central chamber, but in the side
chambers as well, however under microgravity they grew only in the central chamber.
The conclusion of the experiment is that elimination of the effects of gravity
allows the realization of conditions ideal for diffusion.
 
N

NunYa Bidness

Jan 1, 1970
0
You excised "for a little while".

You, sir, are demonstrating most of the characteristics of an idiot.

Good-bye.

Ahh... so you ARE the weakest dink!

Hahahaha...
 
F

Floyd L. Davidson

Jan 1, 1970
0
NunYa Bidness said:
That is what I originally stated, and the other guy refuted...
or seemed to.

Yes he attempted to, which is why I posted my comments
indicating the actual reasons for placement of cabling on poles.
 
J

Jasen Betts

Jan 1, 1970
0
["Followup-To:" header set to sci.electronics.design.]
Nice smack!

but it is bullshit.

at DC the resistance of the conductor (and leakage resistance of the
dielectric) will soon dominate the measured resistance,

the page cited seems to ignore these quantities.
 
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