Space charge accumulation characteristics in double-layered samples simulating DC cable joints

In this paper, we investigated the space charge accumulation properties in double-layered dielectrics composed of EPR placed on top of LDPE, using PEA and Q(t) measurement systems. This was conducted to identify issues when using cable joints which have an interface of different dielectrics for DC transmission. As a result, we confirmed that the electric field was locally enhanced just by placing two different dielectrics when the polarity of the applied electric field was reversed, showing a dangerous state. Furthermore, we used Quantum Chemical Calculation to analyze the experiment results and revealed that this was caused by the difference in trap levels and charge injection barriers of EPR and LDPE.