[AMPS] Ripple current ratings of high voltage caps.

[Rich Measures]

>
>At 09:22 AM 3/4/99 -0800, you wrote:
>
>>>€  However, comparing a ripple-current rating for 105 deg C with a ripple 
>>current rating for 85 degrees C is hardly valid.   My guess is that 105 
>>deg C capacitors are going to last longer in a typical anode supply.  
>>
>I think John's point is that higher max. operating temperature rating seems
>to automatically imply some other performance enhancements over an 85 C
>rated cap, and I can't see that it does.  Choosing the cap with the 105
>deg.C rating, mainly because of that rating,  may be false economy if the
>max ripple current rating is only marginal for the application.  Mallory
>and Phillips still provide the ripple current rating at 85 C, even for
>their 105 C caps. This implies that the max ripple current rating drops
>(substantially ?) as the temp rises from 85 to 105 deg. C (even though the
>'C' and ESR remain stable).   The temp rating only assures that the 'C' and
>ESR will remain within specs up to those temps,  without a permanent change
>in either occurring.  There's no mention of what happens to ripple current
>rating.
>
>There's no indication from either supplier's catalogs that running a cap at
>well below the max design temp will result in longer life,  

€  As I understand it, the lifespan of an electrolytic capacitor approx. 
doubles for each ten degrees C below its rated operating temp.  --  
provided that the temp. stays above the minimum allowable.  

-  later, Phil


Rich...

R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures  


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