>
>
>Rich, AG6K, writes:
>
>>Even if the capacitor is designed for flash discharge service instead of
>>dc filter service, with a 4500 peak-v rating, it should work well at
>>2500v in dc filter service.
>
>Is there a handy rule of thumb as to how much to derate an
>energy-storage capacitor when one wishes to use it in dc filter
>service?
60%
>I understand that the energy-storage types (flash-
>discharge) are designed for ultra-low internal resistance, so
>that they can dump their accumulated joules in a hurry.
The ESR of flash-caps appears to be higher due to use of thinner plate
material - which allows the designer to pack in more C - and more Joules
- per unit of volume.
>I understand, too, that this makes these caps. less than ideal
>for HV power supplies.
They seem to work acceptably in filter service with the 60% derating
figure.
>But I'm a ham. How far ought I to push the envelope with my
>energy-storage caps? Mine are big guys. Do I need to mount
>them in an explosion-proof cabinet to be on the safe side? :-)
- When they fail they typically short without fanfare. Sometimes a case
seam cracks and there is a bit of oil leakage.
cheers, Bob
Rich...
R. L. Measures, 805-386-3734, AG6K
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