[Amps] skin effect

[Gary Schafer]

Skin effect is just as important at 60 hz as it is at RF. At 60 hz one skin
depth is about 1/3 of an inch. It is important in power transmission systems.
Multiple conductors spaced apart are used rather than a single large conductor.
Actually each separate conductor consist of stranded aluminum wire wound on a
steel cable. The strands are for flexibility and the steel cable provides the
strength. Multiple runs of these cables are widely separated. That reduces the
skin effect.

Wires must be insulated from each other to look like multiple conductors. With
regular stranded wire they are shorted to each other.

Skin depth can also become important when there are high currents in conductors.

The following is a note that a friend of mine sent me awhile back concerning
skin effect  and copper weld wire:

"There is a very good article in the Nov/Dec 2000 issue
of QEX concerning
skin effect and losses in
antenna conductors. It has some interesting points
such as the fact that
stranded copperweld is not
as low loss as solid copperweld below 10 Mhz; that
copperweld can be
better (lower loss) that
solid copper under some conditions; and that skin
effect can cause
higher losses on the lower bands
than it does on higher bands, especially at high
current points and
particularly when antennas are
loaded causing higher currents. The reason is the fact
that skin effect
decreases more slowly as the
square root of decreasing frequency while the
conductor length increases
more rapidly in inverse
proportion to decreasing frequency. In other words,
your adding wire at
a faster rate than the
conductor resistance is decreasing."

73
Gary  K4FMX



Joseph DiPietro wrote:

> Steve,
>
> The advantage of regular stranded wire is flexability.
> Litz wire is a special type of stranded wire that is used to reduce skin
> effect.
> At 60Hz the skin effect is not an issue.
>
> Joe D
>
> ----- Original Message -----
> From: "Steve M" <wmoorejr@cox.net>
> To: <amps@contesting.com>
> Sent: Friday, October 04, 2002 2:42 PM
> Subject: [Amps] skin effect
>
> > Hi everybody,
> >
> > Assuming the same gauge, is a stranded conductor better than a solid
> > conductor [less skin effect loss because of multiple conductor surfaces]
> at
> > rf? How about at 60hz?
> >      Also can someone point out a good source for this info on the web?
> I've
> > tried several google searchs with limited results and no answer to the
> > stranded versus solid or tubing conductor.
> >         This subject is a current topic on another reflector. I'm seeing
> > several guys say that stranded is better but I'm wondering if this is so
> > then why don't amp builders use this technique?
> >       I'm thinking that stranded conductors by shorting against each other
> > negate any advantage they might have at very low frequency and are
> actually
> > worse at rf. Am I right, wrong, or clear off base?
> >
> > Thanks
> > 73,
> > Steve  wd0ct
> >
> >
> >
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