Optimization of multilayered insulation performance by regulating temperature-dependent conductivity coefficient

In the flexible DC transmission system, the internal discharge of the optical fiber insulator may be caused by the mismatch of the characteristics between the materials. The conductivity of the outer coating layer varies significantly with temperature, which leads to a particularly serious problem of mismatched conductivity at the optical fiber. In this paper, the outer coating layer was modified by adding nano-AlsOa particles to reduce the conductivity temperature coefficient. The surface potential decay was used to analyze the trap change after the modification of the outer coating layer. The high temperature and high field conductivity test was used to analyze the change of conductivity temperature coefficient after the modification of the outer coating layer. The differential scanning calorimeter was used to analyze the change of glass transition temperature after the modification of the outer coating layer. The results showed that after the incorporation of nano-alumina particles, the deep traps increase, the conductivity temperature coefficient decreases, and the glass transition temperature increases. The conductivity mismatch problem at the fiber surface is reduced.