Development of Gapless Metal Oxide Surge Arresters for 362 KV Gas Insulated Substations

A 362 kV gapless metal oxide surge arrester for gas-insulated substations is described. The active stack consists of 3 parallel 250 cm-long columns, each column made up of ten modules of soldered MOV blocks. Satisfactory thermal performance is achieved by a thermal electric design model, confirmed by thermal mock-up tests and temperature recordings during final prototype tests. Ceramic capacitors are employed for uniform voltage grading. Dielectric design is used to keep electric stress below 4 kV (rms)/mm at maximum expected operating voltage. Laboratory testing of the prototype was performed up to 285 kV (rms) Insulation coordination studies show the advantages of using gapless gas-insulated arresters for improved performance.