Study on the Effect of Temperature on the Self-Healing Behavior of Film Capacitor Dielectrics

Self-healing is imperative for the restoration of the insulation state of metallized film capacitors following breakdown during operation, thereby ensuring the safe and reliable functioning of the capacitors. Temperature is an important factor affecting the self-healing behavior of film capacitor dielectrics, but the mechanism is currently unclear. To investigate the effects of temperature and dielectric matrix on self-healing behavior, polyetherimide (PEI), cycloolefin copolymer (COC), and biaxially oriented polypropylene (BOPP) were selected as research subjects. A systematic study was conducted to examine the self-healing performance at 80, 120, and 150 °C, as well as the effect of self-healing on insulation and energy storage performance. The results showed that as the temperature increased, the capacitance of PEI decreased by 11.90%, 23.00%, and 37.88%, respectively. COC decreased by 11.76%, 7.63%, and 12.18%, respectively, while BOPP decreased by 8.75% and 9.67%, respectively. The accumulation of breakdown holes formed by self-healing decreases, the area of evaporated electrodes decreases, and the boundaries between the evaporated electrode areas formed by self-healing and the surrounding electrodes become more distinct. Furthermore, COC exhibits high dielectric strength, low dielectric loss, and self-healing properties comparable to BOPP at 150 °C, suggesting significant application potential. This research work is of great reference value for establishing the theoretical relationship between the chemical composition of dielectrics and their self-healing ability, and is of great significance for ensuring the safe and reliable operation of capacitors.