RE: [TCML] primary tubing

["Brian" <brianv@xxxxxxxx>]

Gary,
I think it depends on the amount of voltage being dumped into the winding, I
did an FEA simulation using copper ribbon vs copper tubing at 350 volts
primary voltage, and I did see a charge build up at the edges of the ribbon,
now if one is using a pole transformer or NST of 15KV or so, I think there
will be quite a bit of charge build up on the edges, and one may want to
place an insulator over the winding, like plastic plate of some kind to keep
the primary from arcing over to the secondary or place an insulator between
the secondary and primary. I ran the simulation again after placing a
plastic insulator over the primary winding and the charge build up all but
disappeared. I have never used flat ribbon for a primary before so I ran the
simulation to determine if I was going to see a big charge buildup on the
edges and hence big problems but it did not look too bad at this voltage
level.

 And now based on those results my DRSSTC uses a flat ribbon primary with
120Vac input into a voltage doubler and I have not had any flash over
problems without the insulator, but I am only dumping in around 350Vdc or
so. 

--Brian

-----Original Message-----
From: Lau, Gary [mailto:Gary.Lau@xxxxxx] 
Sent: Sunday, November 08, 2009 7:27 PM
To: Tesla Coil Mailing List
Subject: RE: [TCML] primary tubing

I'm not certain that a ribbon conductor is as optimum as it might seem.  I
recall hearing that the current tends to bunch-up towards the edges, much as
skin-effect pushes it towards the outside of a conductor.  But I can't cite
a specific reference to this.

Regards, Gary Lau
MA, USA

> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of G Hunter
> Sent: Sunday, November 08, 2009 5:06 PM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] primary tubing
> 
> <snip>
> As far as the compactness issue of fat Al tube -vs- skinny Cu tube, that
could
> sidestepped by using flat aluminum strap.
> 
> Greg



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