Han, I have lost two similar capacitors running at about 3500vdc over the
years. Both of my capacitors were purchased from Peter Dahl Co and were rated
for 5000vdc working voltage. I came to the conclusion that oil type capacitor
ratings are not as robust as electrolytic type ratings.
I think the failure mode has to do with ripple current and associated
heating. Both failures happened while calling cq for long periods in an EME
contest.
73,
Gerald K5GW
In a message dated 3/6/2008 4:03:05 A.M. Central Standard Time,
higasa@plum.ocn.ne.jp writes:
Recently an old man told me that all of the caps are energy storage jobs
and they are usually derated for continuous duty to about 2/3 rating.
I thank him very much.
I am using cheap 32uF 4500V GE non-pcb caps.
Should I use it at 3000V maximum?
Fortunately I am using this potential level now.
If someone use 16uF 7500V Arioso caps like Henry,
maximum working voltage should be 5000V?
Would you please tell me the reason for the "2/3 derating"
practically when using them for our linear amps?
For a long time I had a question why GE had not indicate working
voltage and test voltage but only "4500V".
Additionally anyone did a destructive/non-destructive test on it?
Seemingly they are sustainable at 5kV, but if the number 2/3 work
their life should be very short.
de Han JE1BMJ
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