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Re: ESR,ESL for common capacitors



Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

At 03:23 PM 4/9/2003 -0600, you wrote:
>Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>
>
>Hi Jim,
>
>Cornell Dubilier usually gives this data straight away (one of the few 
>that do!):
>
>http://www.cornell-dubilier-dot-com/film/9422000.htm
>
>You can struggle and deduce the numbers from the other manufacturers too, 
>but it is not easy to explain all the tricks needed...



>>Maybe a series resistor isn't a good model, although, a constant series 
>>resistor would have increasing DF as frequency goes up, which IS somewhat 
>>realistic.
>
>Series R is fine.  Once you know the Fo frequency of a coil, it is a 
>constant.  See the ESR I use in my models for primary caps:
>
>http://hot-streamer-dot-com/TeslaCoils/MyCoils/BigCoil/BigCoilSCH.gif
>
>http://hot-streamer-dot-com/TeslaCoils/MyCoils/SmallCoil/SmallCoilSCH.gif

But, say you're looking at transient behavior (i.e. fine scale) which is 
wideband.. I notice that Kemet uses a model that represents the dielectric 
loss (the big contributor.. series R of the leads is fairly small) as an RC 
in parallel with the main capacitor.
A typical model might have one branch with 2 nF, 1.1 ohms, and 770 pH in 
series, and a parallel branch with 114 ohms and 6.5 pF in series. (for a 
2.2nF cap at 1MHz)

Of course, Kemet's model changes with frequency, making it hard to do an 
accurate transient analysis with spice.