The service life of large aluminum electrolytic capacitors: Effects of construction and application

Large aluminum electrolytic capacitors are usually selected by considering factors such as cost effectiveness (more ripple current or capacitance per dollar), space effectiveness (less volume per dollar), and performance (more useful life at actual application temperature and voltage). These factors have been addressed in recent years as most major manufacturers have responded with improvements in ripple current ratings, new electrolyte systems, high-capacitance foils, and rigorous cost controls. The focus of this paper will be on some of the constructional and application factors affecting the performance of large electrolytic capacitors-An aluminum electrolytic capacitor must be considered as a complete system since the internal failure mechanisms are multiple and complex in their interactions. It will also be shown that the choices made by the circuit designer can be informed and improved by understanding the tradeoffs between different capacitor series, circuit design parameters, and equipment design enhancements. This understanding can result in designs that are both reliable and cost effective.