Experimental research on space charge of linear / nonlinear double-layered composites

This study deals with the space charge characteristics of linear/nonlinear double-layered composites, and sets out to explore whether the space charge inside linear layer could be suppressed by the nonlinear barrier layer. The linear layer is pure low density polyethylene (LDPE) matrix. The nonlinear barrier layer is prepared by adding nano Zinc Oxide (ZnO) to LDPE with concentrations of 9.09wt%, 13.04wt% and 16.67wt%. The conductivities of nonlinear barrier layer are measured and the nonlinear degree of nonlinear barrier layer, determined by linear fitting through origin software, increase with concentrations of nano ZnO. Space charge distributions of the composite samples are obtained using pulsed electro-acoustic (PEA) method, under different electric field of 10kV/mm, 20kV/mm, 30kV/mm and 40kV/mm at room temperature. Experimental results show that the nonlinear barrier layer plays a role in some degree on the suppression of space charge inside LDPE and effect on the suppression of space charges is significant when the concentration of ZnO up to 16.67wt%. The interface charge of double-layered composites is the primary part comparing with space charge inside insulation, and affect the formation and dissipation of space charge inside linear layer.