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Old 3rd Dec 2018, 11:00 pm   #7
bikerhifinut
Octode
 
Join Date: Nov 2013
Location: Penrith, Cumbria, UK
Posts: 1,993
Default Re: Reservoir capacitors and ripple current.

Quote:
Originally Posted by Ed_Dinning View Post
Hi Andy, have a good dig on the manufacturers website. They normally publish tables of ripple current , ESR, lifespan and temp rating for each of their cap ranges.
We used this a lot in SMPS design.
Note that the same cap in different aspect ratios can have different max current and temp ratings.

I have some of the charts here but they are for older caps, no longer current.
Reduction of cap temp by 10C will double lifespan. Figures quoted on these charts are often for 50 or 100KHZ ripple. 50/100Hz is normally much more benign.
Cheers Ed, that is exactly where I started with all this by downloading the PDF files of the makers data for the capacitors I was interested in. And I did find the specs for 50 and 60 Hz. I already knew about the increase in lifespan by keeping em cool. I tend to try and buy 105 degC caps on that assumption. It was interesting to see the phenomenal increase in life expectancy with reduced temps. The Vishay data showed a lifespan of 700,000 hours at 40 C but down to 3000 hours at 85 which was quite sobering and a good incentive to make the effort to mount the capacitors above decks so to speak in the air.
If I learn something as well as getting the satisfaction of saying "I built that from scratch" it has to be a win win?
I surprised myself when I managed to rewind/alter a heater secondary on a toroid. Admittedly its probably a doddle to you transformer experts but it was a huge leap of faith for me!

A.

Last edited by bikerhifinut; 3rd Dec 2018 at 11:02 pm. Reason: capitalisation and punktuashun.
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