L:   Lifetime expectancy in actual use

L0:  Basic life at maximum operating temperature

Tmax: Maximum operating temperature

Ta:  Actual ambient temperature (around the capacitor)

注:  When Ta is lower than 40℃, the temperature acceleration coefficient is calculated as Ta = 40℃

⊿Tjo:  Internal temperature rise when maximum rated ripple current is applied

⊿Tjo = 10℃:  85℃type

⊿Tjo = 5℃:   105℃type

⊿Tj:  Internal temperature rise when actual ripple current is applied

Note: ⊿Tj should be less than or equal to 30°C. Please let us know when it exceeds 30°C

F:  Frequency coefficient

Io:  Rated ripple current at maximum operating temperature

I:  Actual ripple current

K:  Size coefficient, 1.75≦K≦3.5 (see Table 1 for details)

Va: Actual voltage

Vr: Rated voltage

Ambient temperature calculation formula:

If you have difficulty measuring the ambient temperature (Ta), Ta can be calculated from the capacitor surface temperature as follows: 

Ta:  Calculation on the ambient temperature

Tc:  Capacitor surface temperature

α:  Capacitive component case top to core ratio

Temperature coefficient of rated ripple current

The temperature coefficient shows that when the expected lifetime of the capacitor is almost equal to the rated maximum operating life, the ripple current through the capacitor can exceed the limit of the rated ripple current at each temperature point. When using a temperature coefficient, life extension is no longer expected because the temperature coefficient is the operating temperature set at the same conditions as the maximum life.

Notice: According to the calculation results, the upper limit of life expectancy (L) is 15 years (130,000 hours) over 15 years. There is a certain error in the expected life based on the life calculation formula, which is determined based on our experimental data. Therefore, check to see if the calculated life span far exceeds the design life of the device.

Note: The above load-life calculation is only applicable to Rubycon's Aluminum Electrolytic capacitors. If customers have any other questions or requirements, please feel free to CONTACT US.

Click to download technical information:  Rubycon Aluminum Electrolytic Capacitors – Technical Notes