The reliable application of aluminum electrolytic capacitor mainly focuses on temperature, because the electrolyte of aluminum capacitor is liquid, and the core heating will cause the electrolyte to volatilize, which will eventually dry up in a long time.

 

The temperature rise of the inner core of aluminum capacitor is mainly caused by the loss and heating of ESR and RP resistance (some data regard RP transformation as a part of ESR). Relatively speaking, the loss of RP is far less than that of ESR, so the effect of ESR can be ignored. When capacitors are used in pulse AC circuits, such as power frequency rectifier smoothing filter, switching power input / output filter, etc., the loss and heat generated by ripple current flowing through ESR will seriously affect the service life of the device, because the internal temperature of the device increases, the evaporation of working electrolyte increases, the capacitance capacity decreases, TG δ increases, and the capacitor will dry up in the long term. Therefore, the ripple current value given in the device manual is actually determined by ESR. If ESR is large, the ripple current must be small.

 

Generally, when the electrolyte loss is 40%, the capacity will be reduced by 20%; when the loss is 90%, the capacity will be reduced by 40%. At this time, the core has basically dried up and can no longer be used. From the practical application, evaporation drying only affects the small volume (small capacity, < 10uF) aluminum capacitance (less electrolyte) in high temperature operation (small size aluminum electrolytic capacitance should be used as less as possible in high temperature situations higher than 75 ℃), while for general large capacity aluminum electrolytic capacitance, in most applications, drying will not occur in 10-20 years Failure (in most applications, when the ripple current does not exceed the rated value, the core temperature is not higher than the ambient temperature by 5 ℃; the ambient temperature is between 45 ℃ ~ 55 ℃; in addition, attention shall be paid to the internal core temperature rise caused by high temperature and ripple current or ESR).

 

Due to the large ESR and ESL of aluminum capacitor, it will affect the functional reliability of the circuit when it is not used properly. Ripple current flows through ESR and ESL and produces large ripple voltage. In addition, due to the large size of aluminum capacitor, it is necessary to pay attention not to touch, squeeze or tie the capacitor during installation and transportation.