【description】：the reliable application of aluminum electrolytic capacitor mainly focuses on temperature, because the electrolyte of aluminum capacitor is liquid, and the heating of core will lead to electrolyte volatilization and eventually dry up and fa
the reliable application of aluminum electrolytic
capacitor mainly focuses on temperature, because the electrolyte of aluminum
capacitor is liquid, and the heating of core will lead to electrolyte volatilization and eventually dry up and failure 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 materials regard rp transformation as a part of esr). relatively speaking, the loss of rp is far less than that of esr, so the influence of rp can be ignored and the influence of esr is mainly considered. when capacitors are used in pulsed ac circuits, such as power frequency rectifier smoothing filter, switching power supply input and output filter, 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 rises, the evaporation of working electrolyte increases, the capacitance capacity decreases, and tgδ increases, resulting in the capacitor drying failure in a long time. therefore, the ripple current value given in the device manual is actually determined by esr. if esr is large, ripple current must be allowed to be small.
generally, when the electrolyte loss is 40%, the capacity decreases by 20%; when the electrolyte loss is 90%, the capacity decreases by 40%. at this time, the core has basically dried up and can not be used again. from the practical application, volatilization drying only affects the small volume (small capacity, < 10uf) aluminum capacitor (less electrolyte) operating at high temperature (in the high temperature situation above 75 ℃, the small size aluminum electrolytic capacitor should be used less as far as possible), but for the general large capacity aluminum electrolytic capacitor, in most applications, it will not be dried up 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 ℃ and 55 ℃; in addition, it is still necessary to pay attention to the internal core temperature rise caused by high temperature and excessive ripple current or esr). due to the large esr and esl of aluminum capacitor, it will affect the functional reliability of the circuit if it is not used properly the current flows through esr and esl to produce large ripple voltage. in addition, due to the large size of the aluminum capacitor, attention should be paid not to touch, crush or prick the capacitor during installation and transportation.
