RE: [TCML] Hot Primary

["Lau, Gary" <Gary.Lau@xxxxxx>]

For the observation that inner primary turns get hotter - I believe this is due to the proximity effect, where the magnetic field is progressively more intense on inner turns and tends to constrict the current to an effectively smaller channel.  Not sure if using Litz wire would help here.

Regards, Gary Lau
MA, USA

> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of Dave Leddon
> Sent: Thursday, February 18, 2010 7:11 PM
> To: Tesla Coil Mailing List
> Subject: [TCML] Hot Primary
> 
> As I push my DRSSTC into ever higher currents (presently limited to
> 3000 amps) I am experiencing some significant heating in the primary
> circuit.  I can see that in the future, as we push the envelop with
> even higher power silicon, we may have to resort to water
> cooling.  Even with 3/4-inch od type L soft copper water pipe (was
> that ever a bear to bend) the primary becomes too hot to touch after
> running the coil for one minute.  I even changed the
> interconnecting  wires from #4 to #2 welding cable to prevent
> meltdown, but oddly the larger wire gets just as hot.  I wonder if
> there isn't some sort of rf heating effect unrelated to voltage drop
> which is generating some of the heat.  A related issue which has been
> bugging me for some time, why are the active primary turns
> progressively warmer as you move inward toward the secondary?  One
> would think that all turns carry the same current.
> 
> Dave Leddon
> Pleasanton, CA
> 
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