×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Failure rate for PFC capacitors

Failure rate for PFC capacitors

Failure rate for PFC capacitors

(OP)
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

RE: Failure rate for PFC capacitors

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
 

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources