Re: Higher current same capacitor question

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

Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

Hi Alan,

At 12:20 PM 2/25/2001 +1300, you wrote:
>Hi All,
>
>I have a question to do with capacitor sizes, current capability of the
>transformer,
>cap wear and tear etc.
>
>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?

Probably not.  The RMS current in the caps is proportional to the BPS  If
you double the break rate, the current will also double.  The Panasonic
caps can handle about 3.5 amps RMS per string.

>
>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 .

You can us them together.  Although, they may not add much capacitance or
current handling since they will only add a small part to the capacitance.

If you know the MMCs dimensions and other info, you can find how fact you
can run it. 

>
>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.
>