Installing insulation jacket to improve outdoor insulation performance of composite insulator

In the paper, a new approach is proposed to improve the outdoor insulation properties of transmission lines. It is achieved by installing the insulation jackets and additional grading rings onto transmission line conductors. The impact of insulation jacket parameters on the electrical field distribution along a 220 kV composite insulator was simulated by a finite element program assuming dry surface contamination. The corona inception voltage was measured on real composite insulators and the measurement results verified the conclusion from the simulation. Furthermore, the correlation between the insulation jackets' length and the contamination flashover voltage of composite insulators was studied. Based on the measurement and simulation results, the optimal insulation jacket parameters are suggested. In the last part of this paper, insulation jackets manufactured according to the optimal parameters are installed onto the transmission line conductor in the field. During one year of operation, the positive effect on the electric field distribution and the reliability of the installed insulation jackets have been confirmed.