MMC cap ratings (fwd)

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Moderated and approved by: Gerry Reynolds <greynolds@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Sun, 24 Dec 2006 08:30:26 -0700
From: resonance <resonance@xxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: MMC cap ratings




You can get by with lower ratings, sometimes as low as 2.0 x Erms.

Manufacturers such as Maxwell (now Sorrento Electronics) has always rated 
their industrial caps for 3.0 x Erms.  This insures long life without 
fatigue.  I always use 3.0 x Erms for my cap banks.

If you use a lower rating you risk failure at a critical venture such as a 
demo at a local school, etc.

Due to the relatively low cost of MMC caps and hours of wasted time trying 
to find a few failures or partial failures in a large cap bank, it's usually 
prudent to consider using 3.0 x Erms value for experimenter cap banks.  In 
most cases we are only speaking of 4-5 additional caps, ie, $20 per string 
more to insure a very high quality and long lasting performance from your 
cap bank.

Dr. Resonance



>
> As I recall, isn't the correct rule of thumb to rate a DC cap at 2.8 times
> it's value for ac application? I notice that many coilers run them far 
> lower
> though. I always rate mine at least that much higher.