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Re: Caps DC to AC rating- correction!



Original poster: "kevin wilson by way of Terry Fritz <twftesla-at-uswest-dot-net>" <thebiggiantkevin-at-hotmail-dot-com>

Terry's MMC program does ask for a DC rating, but his MMC power-handling 
program asks for an AC rating. I should have been more specific, sorry!! :-/ 
But my original question still stands. How do I get an AC rating form the DC 
rating? As Ed shows, there can be huge differences at RF.

	This particular discussion seems to relate only to premature
insulation  breakdown due to "overvolting".  Another factor which must
(should be) be considered is that capacitors also have an AC current
rating depending on the construction and effective series resistance.
This has been mentioned here frequently, but probably should be
restated.  The current rating is often given as a function of
frequency.  As an example, I have some 0.25 ufd mica transmitting
capacitors rated at 2500 VDC.  However, the maximum CURRENT rating at
1000 kHz is 50 amps RMS; this would correspond to an RF voltage of only
32!  "Know your capacitors before you use them!"

Ed




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