Development of Station Type Polymeric Metal Oxide Surge Arrester for 500kV AC Systems

The main aspects and technical difficult points in development of station type surge arrester for AC 500kV systems are presented. Two gaskets, providing linear and surface sealing, ensure the sealing of MOA,The leakage rate is less than 6.65 ×10-8Pa·L/s;the pressure-relief device is made on the insulating cylinder taking advantage of its specific performance, As a result the pressure relief test at both 63kA and 800A has passed successfully;Through introduction of grading ring and optimized progressive shunting capacitance at different MOA units, the maximum unevenness of MOA field distribution can be reduced up to 10%～-10%; the mechanical strength of MOA as high as 25.3kN·m.