Lifetime Estimation of Metalized Film Capacitor Based on Self-healing Properties

Metalized film capacitors (MFC) are widely applied in power system, military weapons and railway traffics, etc. The lifetime of MFC is closely related to the self-healing (SH) process, which causes the loss of electrode area and thus leads to the capacitance reduction. As a result, a lifetime estimation method based on the SH properties and statistics was proposed in the present study. To establish the model, the artificial accelerate ageing experiments were firstly performed on the MFC elements under elevated DC voltages, and the capacitance of each element was monitored during the whole ageing periods. At the end of the life with 5% capacitance lost, the aged sample elements were disassembled to achieve the metalized films. Further, the SH parameters including the area of SH points and the points distribution were obtained with the help of image recognition technology. Based on the statistic model of SH parameters and the monitored capacitance reduction during ageing, the duration time of metalized films under certain DC voltage and the SH parameters could be correlated, and in turn the lifetime of metalized films could be deduced. Consequently, an efficient method for the lifetime evaluation of MFC based on the SH properties was proposed.