Influence of Multi-ageing on Electrical Properties of Biaxially Oriented Polypropylene Films

Dry-type film capacitors are the core equipment for smart grids and new energy power generation, and their performance greatly depends on the insulation properties of the internal biaxially oriented polypropylene (BOPP) films. In this paper, multi-physics field aging equipment is applied to conduct electrical-thermal-mechanical aging of BOPP films, and the crystallization characteristics, dielectric properties and trap characteristics of aged BOPP films are studied. The results show that the crystalline form of BOPP film will not change during aging, but shallow traps will be introduced inside, which will promote the decay of surface potential and increase space charge injection. Meanwhile, properly increasing the tensile force (30 N to 40 N) of the BOPP film during electro-thermal aging will increase the dielectric constant and reduce the dielectric loss tangent of the BOPP film, hence restoring the dielectric properties of the BOPP film.