Characteristics on surface flashover of polyethylene nanocomposites film in vacuum

Compared with breakdown strength of insulating material used in power equipments, insulator employed in power system is easy suffered from surface flashover in vacuum. So, surface flashover has become a mainly restricted factor for developing high voltage and efficiency power equipments in vacuum. Although many works have been done to investigate the characteristics of surface flashover in vacuum, there has little work on the surface flashover performance of nanocomposites. This study presents the experimental results of surface flashover characteristics of neat low density polyethylene (LDPE) and LDPE incorporated with Al₂O₃ nanoparticle in vacuum. The flashover measurements were studied under microsecond pulse condition. The voltage and current are obtained from an oscilloscope. In this study, finger shaped electrodes were used and placed over the film samples to initiate surface flashover events. The dielectric spectroscopy of specimens with different particle loadings and the bulk/surface conductivity were also tested. The results of surface flashover voltages as a function of particle loading were presented. The experimental results show that incorporating with appropriate nanoAl₂O₃ particles can improve the surface flashover properties of LDPE in vacuum. The mechanisms of this improvement may associate with the characteristics of nanoparticles and the interfacial region between polymeric matrix and nanoparticles.