Influence of the semiconductive composites doped with Li 4 Ti 5 O 12 on space charge injection in low-density polyethylene

Space charge accumulation in the insulating layers of high voltage direct current cables is the key factor that leads to their degradation and limits the operation safety. Hence, it is necessary to effectively inhibit space charge injection to these layers. In this study, a new method is proposed to suppress the charge injection to cable insulation layer: a certain amount of Li4Ti5O12 nanopowder is doped into the semiconductive screen to enhance the internal conductive network and homogenize the electric field. The influences of Li4Ti5O12 particles in the semiconductive composite screen on the positive temperature coefficient effect and space charge injection process are explored. The obtained results reveal that the charge quantity in the insulation layer corresponding to the minimum peak resistivity is reduced by 49.7%, 58.9%, and 46.9% after polarization at a Li4Ti5O12 content of 4 wt% and electric field strengths of 10, 20, and 30 kV/mm, respectively.