# RE: Current in the Coil -

```Original poster: "Dave Larkin by way of Terry Fritz <twftesla-at-qwest-dot-net>" <teslaman15-at-hotmail-dot-com>

Hi Dave (T), All,

AFAIK the Electrum secondary is only naturally cooled, bear in mind the
secondary was wound with #12!

More generally on this 'rms' current topic - rms currents still seem to be
comparatively poorly understood by many coilers.  Some common misconceptions
are that...

...they are hard to calculate - Wrong! The method to arrive a ballpark value
is pretty simple, although it's probably only good to more than +/- 25%.
It's only simple circuit theory, but for those of you who can't be bothered
to work it out I think someone posted a method a while back.

...the mean and rms. current are the same thing - Wrong!  The mean current,
integrated against time, is very small.  However the definition of rms. is
AC current x having the same heating effect as a DC current of magnitude y.
This means that although the mean current in the tank circuit may only be
some tens or hundreds of milliamps the true rms can easily be 50A or so even
on a comparatively small system.

-Dave-

>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: RE: Current in the Coil -
>Date: Thu, 16 May 2002 20:34:37 -0600
>
>Original poster: "David Thomson by way of Terry Fritz <twftesla-at-qwest-dot-net>"
><dave-at-volantis-dot-org>
>
>Hi Dave L.,
>
>Thanks for the link.  That's quite an input, 2800A!  The peak current in
>the
>Electrum secondary was 61A.  Do you know what kind of secondary coil
>cooling
>mechanism they used, if at all?
>
>Dave T.
>
>-----Original Message-----
>From: Tesla list [mailto:tesla-at-pupman-dot-com]
>Sent: Thursday, May 16, 2002 5:30 PM
>To: tesla-at-pupman-dot-com
>Subject: RE: Current in the Coil -
>
>
>Original poster: "Dave Larkin by way of Terry Fritz <twftesla-at-qwest-dot-net>"
><teslaman15-at-hotmail-dot-com>
>
> >I'm still interested in reading about the coils with the tens of amps
>
>OK - Electrum.  www.lod-dot-org
>
>Secondary base current of 15.98A rms.
>Secondary output current of 37.4A rms.
>
>(the apparent disparity is, I assume, due to different break rates in the
>
> >in the secondary if you happen to think of them.  I think I can easily
> >design a coil with 1mA in the secondary.  The tens of amps coils would
> > >have 10,000 times more current. I could learn a lot from reading about
> > >these monster coils.
>
>Yes, you probably could.
>
>-Dave-
>
> >
> >Dave
>
>
>
>

```