Robert Nichols wrote:
In article ,
Bert Hickman wrote:
:
:For can crushing you need a minimum of about 400 Joules, and for coin
:crushing at least 2000 Joules. I happen to use a bank rated at 140 uF at
:12 kV. I also use Maxwell energy discharge caps, but mine are Series C
:100 kA high current type. Because mine are rated for only 20% voltage
:reversal, I only take the bank up to about 9500 volts (6300 Joules) for
:coin crushing. For can crushing, I only go to about 3500 Joules (mainly
:to reduce wear and tear on the spark gap switch).
:
:Using all of your 15 caps in parallel would give you a capacitor bank
:capable of delivering ~3 kJ, so you are in the right ballpark. However,
:can crushing (especially) and coin crushing can cause highly oscillatory
:discharges. Rapid voltage reversals are very stressful on a HV
:capacitor's dielectric system, and most of Maxwell's pulse caps are only
:rated for 10-20% voltage reversal (at faceplate voltage), so you don't
:want to run these caps anywhere near their full faceplate voltage if you
:are doing can or coin crushing - they WILL prematurely fail. And, you
:definitely don't want to be anywhere near the caps when the energy from
:the other 14 capacitors dump everything they've got into a single
:faulting cap... :^)
:
:Looking at the "Frankenstein" insulator style used on your caps, they
:are likely not rated for more than 2 - 5 kA peak (the folks at General
:Atomics can probably provide you with their actual specs):
:http://www.gaep.com/capacitors.html).
:
:Running more caps in parallel will help to share the peak current seen
:by each capacitor. If you plan to do any coin shrinking, treat the coil
:like a small bomb, with copper shrapnel being ejected at hyper
:velocities.
:
:There's more information on my site:
:http://205.243.100.155/photos/shrinker5.pdf (1 page summary)
:http://205.243.100.155/frames/shrinker.html (more gory details)
:
:And, always remember to be afraid - very afraid - of the energy stored
:in these caps. They will not give you any second chances. =:^[
Ever thought about the effect that might have on a nice chunk
of plutonium?
I'm curious, what would you expect it to be?
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)