PLEASE, dont compare capacitors designed for HV PS use such as in amps, BC
and similar with high ESR caps designed for various energy discharge
applications.
A true oil filled will pretty much last "almost forever" even when run at
its ratings. I have several 40's thru 60's GE, Aerovox and similar in use
here running very cool at close to their marked voltages. That is another
benefit of those good old PCB's; they keep the heat down.
I also have a 53 MF 5KV discharge cap in a compact 3200V at idle PS used
for a UHF 1500W amp. It shows just a small amount of heat during contest
operation.
Carl
KM1H
----- Original Message -----
From: "Barrie Smith" <barrie@centric.net>
To: "Han Higasa" <higasa@plum.ocn.ne.jp>; <amps@contesting.com>
Sent: Thursday, March 06, 2008 1:02 PM
Subject: Re: [Amps] Oil-caps delating 2/3 ratings?
>
>
>
>> 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.
>
> Han:
>
> Totally by accident I ran a pair of these caps at 6500 volts for several
> minutes. Nothing bad happened.
>
> I still use that pair of caps in power supply that runs 4200 volts
> no-load.
>
> As they say, YMMV.
>
> 73, Barrie, W7ALW
>
>
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