RE: PDT (Pig) failure modes

["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 Dave,
         If I were a betting man I'd bet that an adjacent turn-turn 
short is the problem. I've rewound quite a few transformers for much 
lower power levels and this is the common failure mode. It makes a 
joke of massive interlayer insulation and large end-creepage 
distances. 

Regards,
Malcolm


On 21 Sep 2002, at 15:52, Tesla list wrote:

> Original poster: "Dave Hartwick by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <ddhartwick-at-earthlink-dot-net>
> 
> Mark,
> What a beautiful strike! No safety gap-- and no strike rail, I assume
> 
> This PDT (pole distribution transformer) must have been compromised when I
> received it. Something I've not mentioned to the group is the fact that I've
> not put much time on at all.
> Maybe 30-60 minutes total coil run time. Max streamer length has been 50".
> 
> Further analysis of the failure may take place in conjunction with some fine
> list minds like Terry F and Steve Mach. I may send the core to Terry, if I
> can muster the courage for the job.
> I'm psychologically impaired right now, having difficulty making an MOT
> supply  work without transformer arcing.
> 
> Dave
> 
> 
> 
> Original poster: "Mark W. Stolz by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <mark_w_stolz-at-hotmail-dot-com>
> 
> Dave,
> 
> A primary strike is probably not going to hurt your pig.  Here's a shot of a
> nice solid primary hit running ~12kVA.  The coil is a 12", the tank that
> night was around .187uF.
> http://users2.ev1-dot-net/~nmyreality/tesla/AJ010803/primary_strike.jpg
> 
> And no safety gap at all.  This is just one of many strikes I've seen this
> coil take.
> 
> Mark Stolz
> Houston, TX
> 
> 
> >Original poster: "Dave Hartwick by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> ><ddhartwick-at-earthlink-dot-net>
> >
> >David,
> >Yes, but what about the surviving the energy from a primary strike, for
> >example, which can be huge voltage wise? It is not hard to imagine the the
> >insulation used in the core not surviving such voltages. Minor charring may
> >be enough to start the failure ball rolling.
> >
> >My safety gap was not grounded and the system took several primary
> >strikes---juicy ones at about 4 kVA from an 8" secondary. Dr. Resonance
> >seems to think this would be enough.
> >
> >BTW, physically, my PDT does not appear to be very old at all. It looks
> >just
> >like the ones generally in use now, festooning the telephone poles. But who
> >knows the actuall condition of the insulating material inside the core. The
> >dialectric properties of the paper, for example, could be shot, and still
> >physically appear to be normal.
> >Dave
> >
> >
> >
> >Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> ><Tesla729-at-cs-dot-com>
> >
> >Ken, all,
> >
> >I realize ANYTHING manmade will eventually wear out and ultimately
> >fail, but it seems to me that Dave's pig failed LONG before it should
> >have, due to aging! Pigs (PDTs-if you're politically correct:-) are de-
> >signed for the most rigorous electrical and environmental operation
> >and are designed to operate in these harsh environments for 20 to
> >30 years without a hitch. Occasionally there will be a "lemon", but
> >the vast majority of them are like a Timex watch - they'll take a lick-
> >in' and keep on tickin'. Like Terry says, our "coiling" doesn't really
> >even come close to challenging the BIL voltage design envelope of
> >these beast :-) They're designed to withstand direct lightning hits
> >(with the help of  lightning surge arresters) on their primary line
> >inputs and the kickbacks of Tesla coiling are quite puny in energy
> >compared to to lightning bolt-to-line hits ;-) BTW, lightning surge
> >arresters make good substitutes for safety gaps.
> >
> >Coiling in Memphis,
> >David Rieben
> 
> 
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