[Amps] Using an oil capacitor

[Vic K2VCO]

Several respondents to my message have said the same thing. This capacitor cannot be used 
at its voltage rating in filter service and needs to be de-rated to about half its spec'd 
voltage in that case.

I actually have two of these, so I could probably use them in series for a 26.5 uf filter 
capacitor. This would be adequate for a cw transmitter, although I'm not sure if 6% ripple 
wouldn't be audible on SSB. However, two capacitors make a very big package, so I'm 
thinking about going back to the conventional string of electrolytics.

Any recommendations for a source of electrolytics? There are lots of inexpensive ones on 
ebay, but who knows if they are factory rejects!

On 6/19/2011 10:10 AM, Paul Kraemer wrote:
> Vic BE CAREFUL. BE VERY CAREFUL!!!
>  From the size and capacitance you describe it is probably an "energy storage capacitor"
> which is not suitable for power supply filter at even it's published ratings. You will be
> picking pieces of capacitor out of places you really don't want them.
> Paul K0UYA
>
> ----- Original Message ----- From: "Vic K2VCO" <vic at rakefet.com>
> To: "Amps reflector" <amps at contesting.com>
> Sent: Sunday, June 19, 2011 12:59 AM
> Subject: [Amps] Using an oil capacitor
>
>
>> I have an oil capacitor rated at 53 uf 3.5kv. I would like to use it in a power supply
>> with a transformer delivering 2.4 kVAC. The peak voltage is thus close to 3400V.
>>
>> I've never used an oil capacitor before. My line voltage is pretty constant at 240V, but
>> if it were to rise to 250V, the voltage rating of the capacitor would be exceeded. What
>> kind of safety factor do capacitors like this have?
>>
>> The capacitor is 4-1/2" x 4" x 10" and is marked CSI 4W308T. The CSI website
>> <http://www.csicapacitors.com/csite/cms/149.htm> doesn't list this particular one, but
>> other 3.5kV capacitors have similar part numbers. There's no detailed spec. There is this
>> statement:
>>
>> "The WM series of capacitors is designed for general purpose pulse applications in power
>> supplies for lasers, flash tubes and other capacitor discharge circuits where moderate to
>> long life is required."
>>
>> I'm not sure if this is appropriate for power supply filter application. Anybody familiar
>> with these?
>> --
>> Vic, K2VCO
>> Fresno CA
>> http://www.qsl.net/k2vco/
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>

-- 
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/