Experimental Study On The Current-Voltage Characteristic And The Influent Factors Of PE/SiC Composites

Non-linear dielectrics are those materials, for which the electric conductivity and/or relative dielectric constant are/is varied with electric field. Polyethylene (PE) or cross linking polyethylene (XLPE), as a kind of excellent polymer insulating material, are widely used in solid insulation of power cable and other electric equipments, etc. Due to the facilitate processing and simple chemical structure, PE is taken as polymer matrix mixed with silicon carbide (SiC) to prepare non-linear dielectric for the purpose of the basic research in this study. The DC current-voltage characteristic and the influent factors of this composite material are studied and the related conduction mechanisms are discussed also in this paper.The current-voltage characteristics of non-linear dielectrics under different temperatures and pressures are different obviously. The measurement of non-linear composite materials under different temperatures and pressures can be used to distinguish the ionic and the electronic conductivity in non-linear dielectrics. A current-voltage characteristic measuring system with temperature and pressure adjustable for non-linear composites is designed and developed on the basis of existing testing methods. The influent factors of current-voltage characteristics of PE/SiC composites, including electrical pre-stress levels, variety of polymer matrixes (LDPE, LLDPE and HDPE), SiC doping concentration, temperatures, pressures, etc, are considered. The influence of temperatures and pressures on the current-voltage characteristic of PE/SiC composite is emphasized as a key factor in the paper. Meanwhile, based on the experimental results on influent factors and the known electrical conduction mechanism, the conductive behavior of non-linear composite material are discussed.Conduction mechanisms of non-linear composite insulation are deeply understood through the discussion on the experimental results of DC conductivity properties of non-linear composite material in this paper. So the theoretical reference for the microscopic structure design of the composite and development of new function materials is provided.