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Re: Noob Question



Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>



I see what you are saying. With the impedance involved it may never really get to the full 400 kV coil output but could produce enough overpotential on the cap to cause RF tracking off the edge of the foil. If this is occuring at 120 to 400 pps it could lead to localized heating and other undesireable effects on the dielectric.

Dr. Resonance




Original poster: "Dmitry (father dest)" <dest@xxxxxxxxxxx>

Hallo D.C.,

i like your reasoning, but i see one little problem here - you for
some unknown reason have completely removed from the picture safety
gap to ground.
you see - sg is mostly capacitance (btw - its inductanse is much less
than inductance of arc from toroid, coz arc path is much longer than
distance between sg electrodes), so according to law of commutation
voltage on its electrode just can`t suddently jump to 400kv, so most
of this hv would be present only in the arc from toroid to
primary/primary cap. but i know that sg is too slow, so in the end you
can get 2-3 of its breakdown voltage on it - that`s 40-60kv, but not
400kv i guess, so imo your scenario is far from the reality : )


> Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>

> Correct, you are not really charging the cap, however, consider a
> metal plate (one plate of the cap) connected to the primary which
> receives, say, a 400 kV direct strike.

> Momentarily, an increased potential appears on this one plate (the
> one connected directly to the primary via low resistance copper
> tubing).  This will cause increased corona/rf tracking momentarily at
> the edge of the plate (foil) which could trigger a failure.  The
> higher potential is "looking" for a ground and most likely will not
> puncture the dielectric but it will cause failure in the most likely
> mode --- foil edge corona and tracking from the sharp foil edges.

> Most failures in RF caps occur at the foils edge (according to
> Maxwell engineers I have discussed cap failure with) when spikes or
> overpotentials occur.  400 kV even for a short duration would cause
> increased corona leading to failure mechanisms.

> Dr. Resonance


> ----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>

>> > Original poster: Jared E Dwarshuis
>> >
>> > Capacitors die quickly when coils are out of tune, or when you get
>> > primary strikes. (The symptoms you describe do sound a lot like
>> > failing tank capacitors.)
>>
>>I'm unaware of any data or theory showing that primary strikes can
>>threaten a cap. Conservation of energy just won't allow the primary cap
>>to be charged to a voltage exceeding its initial bang voltage.

-----
Let the bass kick! =:-D