[TCML] Primary Capacitance Calculations - "Black Boxes"
k.schraner at vtxmail.ch
Thu Apr 15 20:52:51 MDT 2010
I seem to remember Maxwell pulse caps to be internally buildt as MMC's.
Unfortunately cannot find the link to the TCML postings, which showed
an autopsy or/and X-ray of a Maxwell cap (...by Bert H. or Terry F.?).
Someone remembering too?
I've yet some pic's of a Maxwell 37667 autopsy from Kreso Bukvic
Gary Lau wrote:
> I don't think that the stray lead inductance from an MMC array in any
> way would impact performance. It may be true that an MMC will have a
> higher inductance than a purpose-built pulse cap, but this in no way
> limits performance in our application. If there's an additional few
> nanoHenrys of lead inductance introduced by the cap leads, just reduce
> your primary tap position so that the same net inductance and resonant
> frequency is achieved. Yes, the parasitic inductance is off-axis so
> the pri-sec coupling will theoretically be slightly reduced, but that
> too is easily compensated for (if it was significant) by lowering the
> secondary. Peak currents are unaffected.
> There may be other reasons that an MMC is not the best choice for a
> large coil (economics, size, labor, cost, current rating, etc) , but
> please let's be accurate in citing reasons. Now if you were talking
> about ESR (Resistance), that would matter, but I've seen no data on
> How can you say in general terms that an MMC is rated for only 432A
> Peak without stating the construction details (how many parallel
> Regards, Gary Lau
> MA, USA
> On Tue, Apr 13, 2010 at 12:04 PM, DC Cox <resonance at wildblue.net>
>> Using MMCs with a pole xmfr will present problems. Too many lead
>> connections lead to high relative inductance thus limiting peak
>> currents in the discharge cycle. Also, MMCs are not designed to
>> handle the large peak currents.
>> Best to use a hi-Q factor energy discharge cap rated to do the job
>> ---- minimal internal connections that are accomplished with the
>> extended foil design connections. Typical is a wide foil area with
>> very low inductance connections which permit high peak currents.
>> A typical pole xmfr powered coil, operating with a .06 uF 80 kV
>> energy discharge capacitor will see peak currents of 3,500 Amps (or
>> more) in the discharge cycle. Typically these pulses occur at around
>> 400 pulses per second for best coil performance which again would be
>> a serious strain for an MMC which is rated at 432 Amps peak (max).
>> Dr. Resonance
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