[Amps] AL1500 cooling mod?

Steve Thompson g8gsq at eltac.co.uk
Thu Sep 6 13:55:13 EDT 2007


rt_clay at bellsouth.net wrote:
> While the specified operating temp may indeed be that high, the operating life of the cap decreases with increasing temperature.
> 
> I found the following document,
> 
> http://industrial.rell.com/pdfs/IPG_AN_appguide.pdf 
> 
> which claims on page 15 "For capacitors operating at moderate temperature the operating life doubles for each 10 deg C that operating temperature is reduced."
Yes, that's the number most manufacturers use - but - the starting 
point is typically 2000 hours of life at 105C ambient and maximum 
rated ripple simultaneously. If you come back (say) 20 degrees on 
the temperature and reckon on the ripple current hitting max. for 
25% of the time, then you're at 32,000 hours. That's 3 hours a 
day, every day, for 29 years, or a 24 hour contest every weekend 
for 26 years.

Modern electrolytics are very different from the ones I grew up with!

Steve


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