Effect of BaTiO3 on Electron Emission of Shielding Compound for HVDC Cable

It is essential to suppress the space charge in the insulating layer for the development of HVDC cables. The important role of semiconductive shielding compound is now becoming recognized. In this paper an approach is presented to decrease carrier injection from the semiconductive layer to the insulating layer, by using adding $\text{BaTiO}_{3}$ into semiconductive shielding compound. The resistance-temperature curve of shielding material was measured by four electrode method. The space charge accumulation of polyethylene insulating layer with $\text{BaTiO}_{3}/\text{CB}/\text{EVA}/\text{LDPF}$ shielding compound as electrode was measured by thermal stimulation current method. When the amount of $\text{BaTiO}_{3}$ is 2wt%, the addition of $\text{BaTiO}_{3}$ can significantly inhibit the PTC effect of semi-conductive shielding compound. When the doping amount of $\text{BaTiO}_{3}$ is 2wt%, the resistivity of shielding compound is 50 $\Omega\cdot\text{cm}$ at 90 degrees. The adding of $\text{BaTiO}_{3}$ can decrease the injection of space charge from the electrode of shielding compound into the polyethylene insulating layer.