Design and Test of 500-kV Lightning Protection Insulator

In this paper, based on insulation coordination and simulation, a lightning protection composite insulator is proposed, made up of an insulation part and an arrester part connected in series, whose length is close to that of the standard composite insulator, which met the window size requirements of the tower. The arrester part contains zinc oxide resistors and an internal core rod, which has good explosion-proof performance and tensile strength, in the meantime overcomes the problem that arresters cannot bear the tensile load of transmission lines. Electrical simulations and experiments have shown that the shielding failure current can be released through the proposed lightning protection insulator to the ground and the counterattack current can be prevented from entering the line. The dry-arc distances of the arrester part and the insulation part are 2.4 and 2.2 m respectively, and the grading ring distance is 1.8 m. The maximum AC withstanding voltage reaches 700 kV, and the switching overvoltage impulse withstanding voltage reaches 1200 kV. The proposed insulator can prevent lightning accidents from happening. Moreover, its length, tensile load, and installation mode are the same as existing line insulators, which has the advantages of low cost and ease of installation and maintenance.