Re: Skin Effect

From: 	Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: 	Sunday, August 03, 1997 4:28 PM
To: 	tesla-at-pupman-dot-com
Subject: 	Re: Skin Effect

Hi Robert,
          If I might comment also....
> From:   Robert Davis[SMTP:RE.Davis-at-btinternet-dot-com]
> Sent:   Sunday, August 03, 1997 9:27 AM
> To:     'Tesla List'
> Subject:    RE: Skin Effect
> Sorry the calculation was not clear.  I used the X as multiplication.
> In the second calculation for effective wire resistance the skin depth
> term varies with frequency.  Also the lower case r was a typing 
> mistake.  The ^ symbol meaning, to the power of.  The 66 in the first 
> formula becomes 0.066 after converting skin depth in mm to meters.
> The full equation is given below (without multiplication symbols)
> after substituting the first formula for the skin depth term:
> Dynamic Resistance = L/C((PiR^2)-(Pi(R-(0.066/sqrt(F)))^2))
> Where:
>     F = Frequency (Hz)
>     L = Length of wire (m)
>     R = Radius of Conductor (m)
>     C = Conductivity of copper = 5.8 x 10^7
>     Pi = 3.1415927
> In the above I use sqrt() as the square root function.

Firstly, 66/sqrt(f) gives the skin depth in mm at frequency f for 
copper or at least one grade of it. Resistivity/conductivity is 
already factored into this equation. Seems superfluous to use it