By improving of the dielectric construct between the breakers

medium condition and thermal expansion effect

the breaking capacity of circuit breaker is increased.The main construct of the 252 kV circuit breaker is determined in which double chamber of interrupter construction + dual-direction moving of contacts mode are introduced.The key structure design parameter has been optimized combined with the design experiences of the finalized product: The volume of thermal expansion chamber and puffer chamber as well as the coordination between them are determined which ensures feasibility of the high breaking current.Electric field analysis software is used to calculate

analyze and optimize the electric field strength between the circuit breaker contacts in some sensitive positions.Improving gas flow channel for the decrease of the gas density is restrained and the hot gas exhaust efficiency is increased.As a result

the medium condition is improved.All the test verification has achieved for the researched and developed circuit breaker

and the product have been on stream.In the meantime

it provides the new technical foundation for the various following switchgears.