PROJECTS  Root Cause Analysis of Power Capacitor Failure

A2Z Consulting ltd. team provided Root Cause Analysis (RCA) of film foil power capacitor failure. As a part of the analysis, finite element simulation of electric field at the aluminum foil edges was done. Results of this simulation led us to conclusion, that electric stress in the impregnating oil close to the aluminum foil edges is too high and this electric stress causes formation of partial discharges in the oil. These partial discharges caused accelerated aging of impregnating oil and polypropylene insulating layers, which finally led to an early failure of the capacitor. With the help of finite element simulation, design of capacitor was modified to reduce the high electric field at the foil edges and to prevent early capacitors failures.