Failure rate for PFC capacitors

[hw123]

Dear all

I need some guidelines how to calculate the failure rate for PFC film capacitor.
I know that increase in ambient temperature and increase in voltage, will increase the failure.
Also I think that the current and frequency of the current will have an effect on the failure rate. I just don't know how big the effect will be.
The capacitor is needed for an LCL filter.

Anyone who has an idea.

Thank you

 

[zappedagain]

Check out some of the capacitor manufacturer's web-sites. They will have good articles on their reliability and how it is calculated.

I have an old article from AVX that states the reliabilility lifetime strictly in terms of voltage and temperature:

(operating life / tested life) = (test voltage / operating voltage)^3 * (test temp / operating temp)^8

Note that this formula uses temps in Centigrade so there may be better formulas; the exponents are typical values.

Higher current will dissipate more power in the parasitic resistance (ESR) in the capacitor.

Higher frequency will increase the dynamic power dissipation:

P = freq (Hz) * cap (Farad) * voltage (Volts)^2

Although I believe that's the power dissipated in the driver, so the ESR only dissipates a portion of that within the capacitor package (somebody correct me if I'm wrong on that).

My $0.02

John D