Development of ± 550 kV DC GIS Basin Insulator

ABSTRACT The basin insulator is a core component of the insulation system for ± 550 kV gas‐insulated switchgear (GIS). This paper, using a finite element method for multi‐physics simulations of electric–thermal coupling, determines a geometry suitable for the industrial production of ± 550 kV GIS basin insulators. Results show that, as the temperature increases, the source of charge accumulation on the convex surface of the insulator shifts from conduction current on the gas side to conduction current within the insulator. Surface potential under temperature gradients presents an absolute surface potential value below 5 kV. Mechanical performance tests, as well as electrical tests—including polarity reversal, DC superimposed impulse tests and a three‐month long‐term DC duration test at 1.5 times the rated voltage—were conducted. The developed ± 550 kV GIS basin insulator passed all the tests.