RE: PDT (Pig) failure modes

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

Original poster: "Dave Hartwick by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ddhartwick-at-earthlink-dot-net>

Malcom,
With a turn-to-turn short condition, would you not expect some output,
whether the short exist
in the HV or LV windings? This is not to put into doubt your experience with
xfmr failure modes.
Dave




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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