Re: Shorted turn?

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Justin,

On 13 Oct 2001, at 13:04, Tesla list wrote:

> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<Pyrotrons-at-aol-dot-com>
> 
> Hello Steve and All.
> 
> > Doesn't the toroid on top of the tesla coil act like a shorted turn? 
> 
> > I'm not sure how you'd prevent without causing sharp edges. Perhaps 
> > all that would be required is a small gap that would be sort of self
> >shielded by simply being a very small gap. I don't think I'm describing 
> > what I'm visualizing very well.
> 
> Yes, the toroid does act as a shorted turn, but as you mentioned it is
*most 
> likely* inconsequential. In theory it reduces performance because the turn 
> acts another secondary coil............a one-turn secondary coil.......and 
> will have a strong current induced into it, which is then turned into
heat by 
> the wire's resistance. Heat = loss. 
> 
> As far as I know, noone has "tackled" trying a toroid with a split in it.
I'm 
> sure it's a lot more hassle than it is worth. Shorted turns on a secondary 
> coil are definately not good for performance, we know this already ; )

I tried it about four years ago. There was no obvious impact on coil 
performance and resonant frequency was affected only slightly 
(dropped about 0.5%).

Regards,
malcolm

 
> Usually, shorted turns on the secondary are found down at the bottom end 
> where the coupling is greatest from the primary coil. Shorted turns on the 
> lower end will drastically reduce performance, whereas shorted turns up by 
> the toroid carries a lesser significance.
> 
> A good test would be to take a clipcord and wrap it around the secondary
coil 
> and clip the ends together. Try this at the bottom of the coil and it will 
> get hot from the induced high currents.....
> 
> Try laying it ON the primary and it will melt apart at a kiloVA or so.....
> 
> So I threw in some extra...... ; )
> 
> Justin Hays
> KC5PNP
> G-3 #1150
> Email: pyrotrons-at-aol-dot-com
> Website: www.hvguy-dot-com
> 
> 
> 
>