Re: Why do primaries get hot?

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

Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz <twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>

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?

The wire is not heated by the average current (that is zero,
by the way), but by the RMS current, that is much higher.
A 100 A pulse lasting for 10 us at each 10 ms has an average
value of 0.1 A, but an RMS value of 10 A.

Antonio Carlos M. de Queiroz