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What determines the working voltage of a capacitor?

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Full Member level 5
Apr 14, 2004
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As above.

Is there such a practice whereby people just take a multiplication factor, say 1.5 times or 2.5 times of the normal working voltage? For e.g., if a CAP is to be work in a 5V circuit, its working voltage should be at least 6.3V? Or 10V? Or 15V? ...

Please advice. Thanks!


the maximum voltage specified is the maximum voltage of operation over which the capacitor doesn't sustain any physical damage i.e.if operated above that voltage there maybe change in some of its parameters or even worse the capacitor may get damaged totally....

in low voltage we can easily spot 2 or greater time value but in high voltage like 250 or 600 thi is not INADVISABLE.

For a normal 3V/5V circuit, using CAPs with 10V working voltage is fine, right?
Even choosing a CAP with working voltage up to 50V also does not matter much unless the circuit goes haywire and more than 50V potential across the CAP which might cause explosion of CAP. Am I right?
I just wonder if it is a good practice not to choose a CAP with too high working voltage which is unnecessary or inappropriate!

what you are saying is perfectly right.... as you said you just gotta know what would be maximum possible voltage through the CAP if the circuit goes haywire...

I think the thumb rule of 2xrated voltage for a capacitor is linked to the technology of the capacitor. Chemical capacitor are more sensitive to voltage than plastic or ceramic capacitor and are easily destructed by quick overvoltage pulse.
the second pint is the lifetime : More voltage means an increase in the working temperature, and a decrease of the lifetime of the component....
In my mind, for electrochemical capacitor, we should keep the x2 factor, but we can use the rated voltage for the ceramic ones...

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