Pulse induced failures in bi-axially oriented polypropylene capacitors: Experimental investigation

Abstract

An experimental study of the absorption of high energy pulses in bi-axially oriented polypropylene (BOPP) capacitors is reported in the paper. The pulse handling performance test is used to identify the material or mechanical problem characteristics developed in the capacitor. The experiments are focused on samples of different film metallization and crystallinity and the results are compared in terms of current pulse handling capability as well as the level of impulse breakdown voltage. To assess the impulse handling capability, the proposed deterioration parameter is the number of absorbed pulses and Weibull cumulative probability of failure is presented. Experimental findings reveal specific types of failure development through the gradually elevated energy pulse test. The observed failures are either accidental, or progressive and they are located at the electrode terminal, or in the capacitor volume. The accidental failures are accompanied by no significant change in the additionally measured capacitance and loss factor, however, the characteristic fault location is in the capacitor volume. The progressive failure is caused by the gradual degradation of the insulating material where both the capacitance and the loss factor give a preliminary information of the impending damage, dominantly occurring at the electrode terminals. Possible reasons accounting for the certain failure type are discussed.

Keywords

• Polypropylene
• Capacitor
• Pulse withstand
• Weibull distribution