Re: Why do primaries get hot?

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

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Greg - 

When thinking of skin depth, I've always imagined the currents being carried in
the outer portion of the conductor as a function of the frequency. This
indicates at the operating frequency the wire is broken into two parts (one is
predominantly used, the other negligible and ignored). Each of the two is
smaller than the whole. We can calc skin depth which indicates how much of the
conductor is carrying current and we already know the conductor size. This
suggest a wire size can be found which is equivalent to the conductor carrying
current. This new equivalent size is smaller and R must then be larger. If
carrying the same current, I^2R heating has just been given a boost by the
larger R factor. 

The wire carrying load current is electrically getting smaller with frequency
(that's what I'm trying to say) and still trying to deliver the load current. 

That's my twisted analogy anyway. Take it with a grain of salt. 

Take care, 
Bart 

Tesla list wrote: 
>
> Original poster: "Gregory Hunter by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <ghunter31014-at-yahoo-dot-com> 
>
> Dear List, 
>
> Why do primary coils get warm? I'm aware of the insane 
> current pulses, but they are of only a few uSec 
> duration. The Cu tube coil should integrate the 
> various currents with respect to time, like a heater 
> element, thereby arriving at the average current. The 
> average power supply current of even a monster Tesla 
> coil is under an amp. 1/4" or 3/8" Cu tube should be 
> able to carry a few 100ma all day without warming up. 
> Is it RF heating? 
>
> Cheers, 
>
> Greg 
> <http://hot-streamer-dot-com/greg>http://hot-streamer-dot-com/greg