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Re: Aluminium aka Aluminum Wire (fwd)



---------- Forwarded message ----------
Date: Mon, 01 Oct 2007 22:37:37 -0700
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Aluminium aka Aluminum Wire (fwd)

Hi Ray,

Basic inductance calc's don't bother, but if you wanted to nitpick, 
inductance is the ratio of magnetic flux over current. All inductance 
equations attempt to define this situation. Current flow causes a 
magnetic field in a conductor and thus magnetic flux. When the flux 
density is calculated, both the permeability of free space and the 
permeability of the material are part of the equations that define self 
inductance (see Maxwell, Neumann, etc..). The material is often ignored 
because materials which are not ferromagnetic (copper, silver, aluminum, 
etc..) are near unity. However, use a material that "is" ferromagnetic 
where the permeability of the material is in the several thousands, and 
then you have a situation where the inductance will change with the current.

Coils of the same geometry will be "nearly identical" with inductance. 
RF also has an effect on inductance in a series of windings, but that is 
true for all materials and has to do with current distribution (where 
the current is higher in one portion of the winding than another). And 
yes, losses will change between materials (those losses may or may not 
be enough to worry about).

Take care,
Bart

Tesla list wrote:

>---------- Forwarded message ----------
>Date: Mon, 1 Oct 2007 22:53:01 -0700
>From: Ray von Postel <vonpostel@xxxxxxxxxxx>
>To: Tesla list <tesla@xxxxxxxxxx>
>Subject: Re: Aluminium aka Aluminum Wire (fwd)
>
>I would think that if the metal used in the wire to wind a coil made 
>any difference to the INDUCTANCE, that it would be a factor in 
>equations used to calculate INDUCTANCE.  I don't find it in equations 
>used by NBS/NIST when computing the inductance of standard inductors.  
>Does any one say they have missed something?
>
>Two coils having IDENTICAL geometry, one wound with aluminum and the 
>other copper will have the same INDUCTANCE. However, the losses in the 
>coil wound with aluminum will be higher because it will have a higher 
>resistance.
>
>Similarly, capacitance is not dependent upon the material of the 
>conductor and only upon the geometry.  This assumes the dialectic 
>remains the same in every way.
>
>Resistance,  inductance, and  capacitance are not frequency dependent.  
>It is only when you connect them together in some sort of circuit that 
>frequency effects are noted.  No one has ever built an electrical 
>component where all three were not present.  All you can do is try and 
>minimize or maximize them depending on what you are trying to 
>accomplish.  A good example of what I am talking about is a resistor 
>wound from resistance wire on a ceramic tube.  It not only has 
>resistance but inductance and distributed capacitance.  As such it can 
>be regarded as a high loss solenoid and will exhibit the same 
>characteristics as the secondary of a Tesla coil but in different 
>amounts.  It will be self resonant at some frequency.
>
>As far as aluminum wire is concerned it has its place, but I seem to 
>remember that after WW II a lot of houses were wired with aluminum.  
>Many fires resulted because of poor connections to convenience boxes 
>etc. So, if you are going to use it in coiling it might be well to find 
>out what it takes to make good connections using it.
>
>Cooper-weld wire was developed as an engineering compromise.  Antennas 
>for low frequencies, such as the Beverage, flat top and multi-curtain 
>rhombic become physically large.  The use of copper-weld is a 
>compromise between and among cost, strength, and r. f. resistance.
>
>Ray
>
>
>On Oct 1, 2007, at 7:52 PM, Tesla list wrote:
>
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>
>>---------- Forwarded message ----------
>>Date: Mon, 01 Oct 2007 16:01:41 -0700
>>From: Ed Phillips <evp@xxxxxxxxxxx>
>>To: Tesla list <tesla@xxxxxxxxxx>
>>Subject: Re: Aluminium aka Aluminum Wire (fwd)
>>    
>>
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