Q&A(FAQ) Electrolytic Capacitor Lifetime at Varying Ambient Temperatures.
1. Lifetime Calculation When Conditions Change
Suppose a power supply is used for A hours under condition a, for B hours under condition b, … and for X hours under condition x. Let the estimated lifetime under each condition be La, Lb, …, Lx.
Then the estimated lifetime L under these combined (mixed) conditions is calculated as follows.
2. Example
| Electrolytic capacitor | Rated Temperature = 105°C Basic Lifetime = 1,000H |
|---|---|
| Operating conditions | 45°C (Estimated lifetime = 64,000H) / 8H 55°C (Estimated lifetime = 32,000H) / 8H 65°C (Estimated lifetime = 16,000H) / 8H |
According to formula ①,
The ambient temperature (Ta) used in the above estimated lifetime calculation can be obtained from the following formula.
As a result, Ta (57.2°C) is higher than the average ambient temperature of 55°C, which means that the actual operating condition is more severe than operating continuously at the average ambient temperature.