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Dissipation factor of capacitors

Discussion in 'General Electronics Discussion' started by eem2am, Sep 28, 2010.

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  1. eem2am

    eem2am

    414
    0
    Aug 3, 2009
    hello,

    how can you tell what is the dissipation factor of these capacitors at 100KHz,?

    http://www.produktinfo.conrad.com/d...01-en-METALL_POLYESTER_KONDENSATOR_0_1_UF.pdf

    ...on page 12, the datasheet only says the dissipation factor at 10KHz or 1KHz,....this is not much use since my SMPS switches at 58100Hz.

    i wish to use the 330nF, 400V one close up to the power switch loop, so as i don't draw so much ripple current from the electrolytic cap.
     
  2. shrtrnd

    shrtrnd

    3,802
    507
    Jan 15, 2010
    If the data sheet doesn't show a graph to find your freq, email EPCOS, and ask them about your specific application.
    I use a lot of metallized polyester for RF applications, so I assume you're ok. But it's
    possible the construction of this particular cap is not designed for the frequency you're planning to operate at. The manufacturer can tell you if this is the cap for you, or recommend a better model.
    (like ceramic maybe?)
     
  3. Militoy

    Militoy

    180
    0
    Aug 24, 2010
    I don't know if you've looked at Epcos' general data for film caps yet - but it has a pretty good explanation of the effects of higher frequencies on these caps. the issue isn't so much that you are limited to 10 KHz operation - that's just the standard test frequency for higher value polyester caps. I think their stacked polyester caps are pretty good at HF. Look over their charts - and if you are still concerned - consider going with a polypropylene or ceramic cap instead.

    http://www.epcos.com/web/generator/...__en.pdf;/PDF_GeneralTechnicalInformation.pdf
     
    Last edited: Sep 29, 2010
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