Re: chokes

["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 Ed, Terry,
               Whether the transformer is producing the voltage or 
there is a transient fed in at the secondary terminals, the top layer 
of the winding is surely the most likely place where an internal arc 
would start. ?

Regards,
malcolm

On 4 Oct 2001, at 18:28, Tesla list wrote:

> Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<evp-at-pacbell-dot-net>
> 
> > I don't know how to do it either...  The high voltage on the outer windings
> > "thing" is an unproven theory.  Failed NSTs do seem to blow on the outside
> > winding.  That is also a high voltage gradient area without any doubt as
> > well.  The inductance of that outside layer combined with the say 300kHz
> > can drop a lot of voltage on the winding but there also needs to be a place
> > for the current to flow which would have to be from inter layer capacitance
> > I would think.  Judging from how complex the secondary has been shown to be
> > from Paul's work, I bet this is far worse to model.
> > 
> > However, if one had a secondary winding exposed, a signal generator, and a
> > high impedance scope probe...,  one could inject a say 300kHz signal into
> > the winding and measure the voltage drop.  That would give a very good idea
> > as to what proportion of an incoming signal gets dropped into the outer
> > winding.  A good thing for that half blown depotted NST sitting on the
shelf.
> > 
> > I have the generator and the scope stuff but since I use protection filters
> > I don't have any blown NSTs :o)))
> > If anyone has a spare old NST winding they could send me, I could give it a
> > test (terellf-at-qwest-dot-net ;-)).  I could figure out a temporary core to stick
> > in it so only the single NST winding itself would be needed.  I would have
> > to scratch into the wire to make contact so it may ruin the winding.
> > 
> > There is also a nasty high voltage spike at the beginning of gap condution
> > that is rich in up to GHz harmonics, but will will just try crawling
> first ;-))
> > 
> > Cheers,
> > 
> >         Terry
> 
> 	I suspect that there are guys designing high power pulse and power
> transformers who could handle that sort of thing.  Certainly they must
> be interested in the voltage distribution resulting from a lightning
> strike, for example.  Guess we don't have any power engineers and
> transformer designers in the group (they're getting pretty scarce
> anywhere these days) or someone would have spoken up.  As for the CS
> measurements, I think a lot could be learned if you could somehow dig
> into the transformer and measure voltage distribution without wrecking
> it.  Impossible, of course.  Hope there'll be other information on this
> subject.
> 
> Ed
> 
> 
> 
>