Abstract: After an analysis of the structure and properties of the DC joints insulation components, the generation mechanisms and the measurements methods of the space charge in DC multilayer joints are presented. Then, the equations used to calculate the charge accumulated at the homogeneous interfaces of the joints and the electric field are given. To calculate the space charge density and the electric field, experiments on flat samples (XLPE and reduction EPDM) are performed and their dielectric properties are measured. Finally, it is shown that the charge accumulation leads to local enhancements of the electric field and to degradation and lifetime reduction of joints.
Keywords: hvdc cable joints, aging, interfaces, space charge, electric field