Dielectric properties of nano TiO₂/liquid silicone rubber composites for direct current cable accessories insulation

In the operation of power system, the electric field in high voltage direct current cable accessories was easily distorted and even leades to insulation failure, which was caused by the conductivity of composite insulation materials mismatched. In order to solve this problem, the nano TiO₂/liquid silicone rubber (LSR) composites with different components for cable accessories insulation were prepared, and the microstructure and dielectric properties were tested. The results show that nano TiO₂ particles disperse uniformly in LSR matrix. With the increase of TiO₂ nanoparticles doping content, the relative permittivity and dielectric loss constant of nano TiO₂/LSR composites are increased, while the breakdown strength decreases. The conductivity of nano TiO₂/LSR composites is approximately equal to that of cable ontology insulation crosslinked polyethylene (XLPE), when the nano TiO₂ doping content is 4wt%. Moreover, the trend of the conductivity changes of the two materials is basically the same, as the electric field strength increases. The pulsed electroacoustic apparatus (PEA) test result shows that 4wt% TiO₂/LSR composites accumulated space charge is the least. The doping of TiO₂ nanoparticles improves the electric field dependent coefficient of conductivity of cable access-ories insulation, and it can inhibit the accumulation of space charge to some extent. It makes the composite insulation achieve a good match, which can promote the electric field distribution uniform in the direct current cables accessories composite insulation.