Application reliability selection of military electrolytic capacitor (II)

2. Reliability application of electrolytic capacitor

Reduce the working voltage properly.

Reducing the working voltage of electrolytic capacitors is the most effective way to extend the service life of capacitors and improve reliability. Because the failure rate of electrolytic capacitor is directly proportional to the two power ratio of the applied voltage and the rated voltage of the capacitor. The electric capacitor is used in the power filter circuit most, the input voltage changes or the load is suddenly open, the voltage of the filter capacitor will change. If the design is not carried out, it is likely to make the capacitor breakdown. In addition, the AC voltage from the input is not a sine wave voltage, and the peak voltage of the normal non sinusoidal wave is higher than the sine wave voltage. It can greatly influence the life and reliability of the capacitor. Therefore, the working voltage of the electrolytic capacitor should be greatly reduced when it is used. The magnitude of the voltage drop of electrolytic capacitors depends on the reliability requirements of the whole machine and the specific circuit used by the capacitor. Generally, it can be divided into three levels, the first level is 50% of rated voltage, two is 60%, and three is 70%. The capacitor with high voltage and large capacity should choose a larger reduction range. The larger the capacitance of the capacitor, the larger the area of the oxide film, the greater the probability of occurrence of dielectric defects, and the lower the reliability.