Design of Current Gate Width in AC Segment Metalized Film Capacitors Based on Self-Healing Characteristics

Segmented electrode technology is widely used in metalized film capacitors (MFCs) to limit self-healing energy and prevent self-healing failure. However, there is still a lack of research works on the design of the current gate width for ac segmented MFCs. In this article, an experimental platform is built to investigate the current flowing through the breakdown spot under ac voltage, and the effect of different factors on the current action integral is studied. The results reveal that the parallel capacitance has a little effect on the current action integral in the range of 10– $160~\mu \text{F}$ ; the current action integral is negatively correlated with the interlayer pressure in the range of 20–800 kPa and the temperature in the range of −20 °C to 90 °C, while positively correlated with the voltage in the range of 950–1150 V and film thickness in the range of 7– $10~\mu \text{m}$ . The fusing criterion of the current gate is also studied experimentally. It is found that for a 1.5 mm wide current gate with square resistance $\beta = 2~\Omega / \Box $ , the current action integral should not exceed $3.295\times 10^{-5}\,\,\text{A}^{2}\text{s}$ . The design method of the current gate width of segmented MFCs is proposed, and the rationality of the design method is verified by experiments. The research results will provide guidance for the design of the current gate width for segmented MFCs.