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Re: [Amps] Oil-caps delating 2/3 ratings?

To: "Barrie Smith" <>, "Han Higasa" <>, <>
Subject: Re: [Amps] Oil-caps delating 2/3 ratings?
From: "jeremy-ca" <>
Date: Thu, 6 Mar 2008 14:31:51 -0500
List-post: <">>
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 

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 


----- Original Message ----- 
From: "Barrie Smith" <>
To: "Han Higasa" <>; <>
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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