The effect of temperature on space charge accumulated at chemical and physical interfaces of HVDC polymeric insulation systems

This paper analyzes the behaviour of dielectric interfaces on space charge trapping features of electrical insulation systems. In particular, results of space charge measurements performed at different temperatures on chemical and physical interfaces of dual-dielectric minicables are here presented and discussed. Interfacial polarization due to conductivity/permittivity mismatch between different insulations is investigated together with the charge accumulation at the interface due to injection from the electrodes. The presence of interfaces, particularly physical interfaces, seems to give rise to a significant space charge build-up, which, in turn, is able to distort the actual electric field, overstressing the insulation with respect to the design field.