Development of 550 kV-8000 A composite insulator gas bushing

A composite insulator gas bushing of 550 kV-8000 A, one of the commonly used largest sizes, has been designed, and various verification tests have been carried out. The rounded shed tip of the hollow insulator makes the bushing partial discharge free up to 635 kV (2E). A creepage distance of 20500 mm lets the bushing withstand the clean fog test with a pollution class of 0.12 mg/cm/sup 2/, and with an applied voltage of 572 kV (1.8E). Taking advantages of the cylindrical shape of the composite hollow insulator, successful thermal design is realized to flow 8000 A without a heat radiator. Sufficient mechanical performance is observed in seismic tests.