Evolution Characteristics of DC Breakdown for Biaxially Oriented Polypropylene Films

Biaxially oriented polypropylene (BOPP) films are the preferred storage dielectric for dry-type film capacitors due to excellent dielectric properties. However, the evolution characteristics of dc breakdown of BOPP film in air remain unclear. This study focuses on the influence of curvature, contact area and material of electrode on the dc breakdown in BOPP films. The on- line/off-line measurements of surface potential and characterizations of trap distribution are achieved. And the simulations of surface charge, electric field, and energy injection are accomplished. The breakdown path and degradation traces in BOPP films are also analyzed. The experimental results show that the effective insulation distance is the key to determine the actual performance of the film, affected by the trap distribution and density. This article has a reference for the optimization of insulation structure for dry-type film capacitors in the field of high-voltage direct current (HVDC).