RE: Higher current same capacitor question

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

Original poster: "David Dean by way of Terry Fritz <twftesla-at-uswest-dot-net>" <deano-at-corridor-dot-net>

Hi Allen,

First thing let me say that the Resonant size for a pig or PT is irrelevant.
The ballast determines the resonant point. 36.7 mH in series with the low
voltage winding of the distribution transformer would make it resonant with
a 40nF tank cap at 50Hz. More inductance gives the appearance of LTR. Less
inductance gives the appearance of STR.

later

deano



>  I have a Tesla Coil that is designed for a 15kV rms 120mA NST
> farm using a
>  40nF
>  MMC capacitor. I have recently aquired a 11kV rms 5kVA power distribution
>  transformer, and I am wondering if I can take advantage of the increased
>  current capabiltiy of the power transformer.
>
>  My power supply is 230 V, 50Hz, 20 Amps max, which corresponds to
>  418mA on the secondary of the power transformer.
>
>  My 40 nF capacitor is way under resonant size for this transformer,
>  which is 121 nF  !!
>
>  Question 1: I have a static spark gap, so could I set the gap to fire at
>  10-11kV
>  and let the system run at an insanely high bps without damage to the MMC?
>  Would the RMS current on the capacitor be way over their rating?
>  Can I use the full current capability of this transformer with risking
>  damage to the MMC?
>
>  Question 2: I have two oil-filled plate caps that are not currently being
>  used. However, I suspect that I CAN'T use the plate caps and the MMC
>  together at all because of the differing dv/dt's of the
> capacitors - the MMC
>  will discharge very fast and then the plate caps will expend energy
>  re-charging the MMC. Is this correct ?The plate capacitors are
> 15kV DC 11 nF
>  and        30 kV DC 5nF .
>
>  Comments ? Suggestions ?
>  Being a student, I can't buy any more MMC caps for a long while,
> and I can't
>  afford to break the MMC I have.
>
>  Thank you very much,
>  Alan Williams.
>   >>
> Alan,
>
> I believe you will need to go to a rotary gap with this much
> input current.
> My experience is that most static gaps will not provide adequate
> quenching
> (i.e. will fire and stay power arced) above about 2kva.  Some on
> this list
> have forced air quenched static gaps running at high power
> levels, but most
> switch to a rotary gap when using distributition transformers for power.
>
> Your .04 ufd cap should work just fine.  You might look at Terry's mmc
> calculator to check the AC current rating.  Add more capacitance
> as you have
> money - and retune the system of course.  Increasing primary
> capacitance will
> produce longer sparks.  If you do go to a rotary gap, you should
> put a safety
> gap across it to save the caps from any problems.
>
> Ed Sonderman
>
>
>