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RE: Maxwell Capacitor abuse
Maxwell doesn't specify AC or DC. Mine are just labeled 45KV.
The Maxwell web site has some interesting data relating voltage reversals
and voltage to expected life. A new Maxwell double-ended cap is rated at
10^8 (a few are rated 10^9) discharge cycles at the rated voltage, with a
20% voltage reversal. A chart at:
http://www.maxwell-dot-com/energy/comp_syst/products
<http://www.maxwell-dot-com/energy/comp_syst/products> , (look for High voltage
capacitors -> Next -> Series PD -> "Basic Cap Facts") shows what happens
when one increases the voltage reversal. At the rated 20% reversal, the
coefficient is 1.0. At 50% the coefficient is 0.15 (i.e. rated at 0.15 x
10^8 discharge cycles). At 70% it is 0.037. The chart doesn't go beyond
80%. Not sure how to quantify voltage reversal in our application, but it's
certainly a lot more than 20%. Clearly a fast-quenching system will last
longer.
On the up-side, another chart relates charging voltage with life expectancy.
Exceeding the rated voltage by 20% reduces the life by 50%. But running at
70% of the rated voltage will increase the life by a factor of 10! Running
at about 54% of the rated voltage will increase the life by a factor of
100!! And 40% of the voltage will get you 1000 times the life!!!
Gary Lau
Waltham, MA USA
>If the Maxwell's are AC rated, then they are rated plenty high enough
>for a 12/30 NST. Mine are rated at 45kVAC , and I often apply 32kV
>peak, or 23kV RMS.