Lifetime of film capacitors?

[treez]

Hi,

The following discusses lifetime of film capacitors…
https://www.vishay.com/docs/48164/_did-you-know_dclink_vmn-ms7369.pdf

Generally , it appears a Film capacitor can do 100,000 hrs at 70degC as long as operating voltage is less than 70% of V(nominal).
Do you know if this refers to with full rated ripple current flowing in it? Also, does 70degC refer to internal temperature, or ambient temperature?

For example, the MKP1848S71050JY6F (100uF, 500V) film, capacitor is rated for 22A of ripple current........
MKP1848 series datasheet:
https://www.vishay.com/docs/26010/mkp1848sdclink.pdf


This was also in part discussed here, but slightly differerently……
https://www.edaboard.com/threads/lifetime-of-electrolytic-capacitors-vs-film-capacitors.377587/

 

[biswaIITH]

Hi,

The following discusses lifetime of film capacitors…
https://www.vishay.com/docs/48164/_did-you-know_dclink_vmn-ms7369.pdf

Generally , it appears a Film capacitor can do 100,000 hrs at 70degC as long as operating voltage is less than 70% of V(nominal).
Do you know if this refers to with full rated ripple current flowing in it? Also, does 70degC refer to internal temperature, or ambient temperature?

For example, the MKP1848S71050JY6F (100uF, 500V) film, capacitor is rated for 22A of ripple current........
MKP1848 series datasheet:
https://www.vishay.com/docs/26010/mkp1848sdclink.pdf


This was also in part discussed here, but slightly differerently……
https://www.edaboard.com/threads/lifetime-of-electrolytic-capacitors-vs-film-capacitors.377587/

You can refer this for life estimation of film capacitor & also a good read

 

[c_mitra]

Hi,

The following discusses lifetime of film capacitors…
https://www.vishay.com/docs/48164/_did-you-know_dclink_vmn-ms7369.pdf

Generally , it appears a Film capacitor can do 100,000 hrs at 70degC as long as operating voltage is less than 70% of V(nominal).
Do you know if this refers to with full rated ripple current flowing in it? Also, does 70degC refer to internal temperature, or ambient temperature?

For example, the MKP1848S71050JY6F (100uF, 500V) film, capacitor is rated for 22A of ripple current........
MKP1848 series datasheet:
https://www.vishay.com/docs/26010/mkp1848sdclink.pdf


This was also in part discussed here, but slightly differerently……
https://www.edaboard.com/threads/lifetime-of-electrolytic-capacitors-vs-film-capacitors.377587/

Obviously you did not put the capacitor under test for 100,000 hours! These numbers are results of modeling.

The failure rate (ignore infant deaths) is exponential, follows a Poisson process. The failure rate is dependent on the temp (needs some activation energy)- the reciprocal of the temp. The higher the temp the greater is the failure rate.

The applied voltage is the stress applied on the dielectric and that is also exponentially related to the failure. On a semi-log paper, exponential graph will look like a straight line.

In short, you need not worry too much about the exact number (e.g., 100,000 hrs >10 years) simply says that average life is 100,000 hrs in a stochastic sense; if you start with 100 capacitors with the same test condition, 69 will live longer than 10 years. The chance that a given cap will fail in one year will be about 0.09. But there may be other components that may fail before that!

 

[Easy peasy]

It is VERY much determined by the quality of the zinc end spray on the caps - this can vary widely b/n manufacturers ...!

Vishay etc last a lot longer than brands form the north west pacific ...