RE: Electrical Properties of Aluminum and Network Analyzer was : RE: Brass

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>

Hi Gary,

At 09:28 PM 4/21/2003 -0400, you wrote:

>I disagree.  The fundamental circuit elements in a real primary inductor, 
>Rdc, Rac, L, and C, are all linear.  At any given frequency, these 
>parameters are constant regardless of voltage or current levels.

Actually, I have seen those skin depth vs. current graphs too and they are 
pretty dramatic.  Darned if I can't find any on the net now ;-p  Saw a good 
one just yesterday...  But we are talking like hundreds of amps...   Maybe 
Dan knows some good links on this...

>If there is some _significant_ loss mechanism that is non-linear, I'm not 
>aware of it and I would be interested to learn more if you know of one.

I think it is due to the increasingly significant magnetic fields, sort of 
like super conductors start messing up at high currents.  But I ain't no 
genius in this area...

>Corona losses are not linear, but for similar coil geometries, an Al coil 
>would have the same corona losses as a Cu coil.  A curve plotting AC 
>resistance vs. frequency on a network analyzer for similarly constructed 
>copper and aluminum inductors would be a definitive comparison.  If AC 
>resistance of the Al coil is higher on the network analyzer, it most 
>certainly will have comparably higher losses in a TC tank.  How much an x% 
>increase in primary AC resistance may impact the secondary spark length is 
>still an open question however.

Yes!  Your coil comparisons are the best out there I know of!!  We can sort 
of extrapolate those up.  If it does bad on your test, it will do double 
bad at 2000 amps!


>Terry wrote:
> >Radio Shack sells like 10 gage aluminum ground wire for TV antennas.  Bare
> >copper wire of the same gage is common.  Just making a coil of each and run
> >them in a high RMS current primary circuit (secondary system not needed)
> >would do it.  I have too many things going on at the moment, but maybe
> >someone else ;-))
>
>It was my plan to construct an aluminum coil for my series of network 
>analyzer AC resistance measurements, but I came up empty searching at Home 
>Depot and flea markets for Al wire.  Radio Shack - I never would have 
>guessed!  Their web site describes a 40 ft roll of 8 gauge aluminum ground 
>wire.  That sounds a bit stiff, but I'll check it out and see.  If they 
>stock it and if it is solid, I will construct and network-analyze an 
>aluminum primary, both before and after a salt-water soak.

It is a very old product that all RS stores will have ;-))  It is solid and 
very soft.  All my chain link fences are held together with it :o))  I 
looked around and aluminum tubing in 1/4 x 50 foot rolls appears not to 
exist...  Let me know if you have trouble finding it and I'll go get it for 
you!

Super cool that you can test this!!!!  Your comparisons are the only good 
information we have on such things!  I really appreciate your work in 
this!!!  Primary circuit losses are critical, so this info is very much 
needed!!

I also have a full spool of #24 Al magnet wire if that is of any 
use.  Robert Stephens sent it to me once but I was bad and never did any 
testing with it :-(

Cheers,

         Terry


>Regards, Gary Lau
>MA, USA