High-voltage grade vacuum circuit breaker is the development direction of environment-friendly circuit breaker. Tank multi-break circuit breaker is an effective measure to realize ultra-high-voltage vacuum circuit breaker. In order to improve the insulation level of tank single-break vacuum arc chamber and meet the demands of compact pressure equalization of tank multi-break vacuum arc chamber

this paper proposes a new structure of 126 kV integrated self-equalizing vacuum arc chamber. The ring ceramic pressure equalizing capacitor is arranged on the outside of the 126 kV vacuum arc chamber through the external shielding cover and the pressure equalizing ring coaxially

which has the function of shielding cover pressure equalization and break pressure equalization. The electric field model of the integrated self-equalizing vacuum arc chamber is established

and the electric field analysis is carried out. The advantages of the structure and the traditional structure in the electric field distribution characteristics are compared. The design of the ring ceramic pressure equalizing capacitor is carried out combined with the manufacturing process. The research shows that the self-equalizing structure can improve the insulation strength of tank single-break vacuum arc chamber by 11.6%

and meet the demands of compact pressure equalization of tank double-break vacuum arc chamber. This sthudy can provide a design basis for the development of special vacuum interrupters for the series connection of can-type multi-outlet vacuum circuit breakers of voltage level above 252 kV.