Re: cap specs or non-specs
Tesla List wrote:
> >From PikeGreen-at-multipro-dot-comSat Jun 22 22:41:46 1996
> Date: Sat, 22 Jun 1996 20:31:04 -0500
> From: Pike Green <PikeGreen-at-multipro-dot-com>
> To: "'tesla-at-pupman-dot-com'" <tesla-at-pupman-dot-com>
> Subject: RE: cap specs or non-specs
> Rob, Richard H., and All,
> Rob wrote:
> I have worked as both a product engineer and a test engineer, so I am
> proposing that this group form its own specification for caps. This
> can't be that difficult, and might extend the state-of-the-art. Who
> knows, the next "black budget" gov. project might reference telsa
> group cap specs for some exotic cap application.
> Richard Hull wrote:
> I always spell out every spec to my cap maker and demand impulse
> tests prior to shipment.
> Perhaps Richard could also post his specs.
My specs vary based on what I plan to do with the capacitor and therefore
I can't publish specific specs. I will note that the tighter and more
severe the specs,(the more you constrain the builder), the more you will
have to pay.
My object is to the let the cap maker go ape!! I typically say up
front..."I dont care about the case type, its size, its composition or
the output leads as long as it is the bottom of their line and cheapest
form." I tell them to write this spec down well as it is the prime
I now proceed to outline the key points about how I'm gonna try and
destroy whatever they send me!!
The #1 spec is break rate or pulses per second. Next, the fact that a
60hz AC sine wave will be the source of power applied and that no DC will
ever be applied! Also I tell them that major reversals of current can
occur at any time. Furthermore that the current peaks might exceed
20,000 amps, but usually will be held below 2,000 amps (This usually
sends a few shivers up their spines) I next give the peak voltage
expected in the sine. I then state that whatever they figure for the
voltage standoff in this proposed killer service, I want that safe and
optimum design voltage doubled in the cap that they send to me or don't
bother sending anything.
I tell them to assume a total average .00001% duty cycle, in service.
(They usually freak out here) This is like saying I want a 3,000 hp
Allison engine , but I'll only run it 3 seconds a month. This forces
them to overdesign the thing and puts it into perspective that you are
basically impulse testing there cap. (trying you best to blow it up)
The killer specs force overdesign (expensive, normally), but the latitude
in case design and unlimited size allows them to design a large safety
margin into the cap which might not otherwise be possible in a cramped
case made of metal. (vastly cheapens the design)
I usually wind up with a large solid monolithic ugly gray plastic block
with female 1/2", threaded, recessed terminals on it. T'ain't purdy but
lasts a long time in Tesla service. I haven't killed a custom
manufactured unit yet!
Richard Hull, TCBOR