Effect of Nano-TiO2 filling on partial discharge properties in air gap defects for cable terminations

Partial discharge (PD) is one of the major reasons for the insulation deterioration of the cable terminations. To avoid the rapid deterioration of the insulation caused by PD in air gap defects, a new method by filling nano-TiO₂ particles in air gap defects to suppress the PD of the cable terminations. The typical defects are designed and the cable accessories accelerated aging and testing system are used to obtain the PD characteristics of the terminations under different aging time, and the surface morphology of the defects is analyzed by use of the scanning electron microscope (SEM). Moreover, this paper make a finite element model of the air gap defects in the cross-linked polyethylene (XLPE) insulation to discuss the impact mechanism of the nano-TiO₂ particles to the PD activity and surface morphology of the defects. The study results show that the discharge energy of the PD reduces significantly and the growth trend of the discharge amplitude and the discharge repetition rate are not obvious after filling. In addition, the surface of the defects is smooth and the carbon content of the test area decreases significantly by filling nano-TiO₂ particles. The results indicate that filling the nano-TiO₂ particles in air gap defects can effectively improve the PD properties in defects for the cable terminations.