Effects of fluorination on surface charge behavior of polypropylene films under pulse voltage

Polypropylene (PP), with low loss and high dielectric strength, is widely used as dielectric for the metallized film capacitor (MFC). The electric aging and dielectric breakdown of the dielectrics under high voltage stress is a major concern in the research on polymer materials. Surface discharge and flashover may happen on the PP film between the metallized segments in MFCs, which can lead to the breakdown of insulation. The effects of direct fluorination on the surface charge and flashover characteristics of PP films under pulse voltage are experimented in this paper. The experimental results indicated that the surface charge and flashover voltage were strongly correlated with the charge polarity, pulse frequency and fluorination time. It was suggested that the fluorination of certain time could significantly improve the decay rate of the surface charge as well as the surface flashover voltage of PP samples.