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Insulation Properties Improvement of Polypropylene Films by Crystallization Regulation

Metallized film capacitors are the core equipment of converter stations and the polypropylene (PP) films act as the main insulation. The microstructure of polypropylene films will be damaged in the long-term operation under DC voltage and eventually leads to insulation failures. In this paper, the PP films were prepared with different contents of nucleating agent. The micromorphology was observed and the crystallization properties were investigated. The breakdown experiments were conducted and the average DC breakdown strength of the PP film with 0.01 wt.% nucleating agent is increased by approximately 25.7% compared with that of the original sample. The conclusion can be drawn that the improvement of the insulation performance through crystallization control is feasible and shows a great potential in practical applications.