In view of the problem that operation reliability of the circuit breaker is affected due to excessive tripping force and excessive or small amount of buckling after the accumulation of tolerances of the parts of operating mechanism for the circuit breaker several key parts affecting closing reliability are found out through the force analysis of the transmission chain of the tripping part of the mechanism.The influence of the amount of buckling on the closing and tripping is analyzed and the dimensional chain of the buckling of the closing and tripping system is drawn.The tolerance chain calculation of the buckling amount of the mechanism in the charge holding condition is performed

finding that the tolerance fit of the existing product does not meet the value range of the buckling amount under the condition of complete interchange.Through the simulation analysis of the tolerance chain

the key parts and dimensions affecting the closing and tripping force and the amount of buckling are found out and the key parts and their dimensions affecting the sensitivity and contribution of the tripping force and the amount of buckling are obtained.The optimization design of the existing design tolerances is performed and the tolerance chain of the product fully meeting the technical parameters under the condition of complete interchange is achieved.Finally

the problem of parts tolerance affecting the reliable closing operation of the circuit breaker is solved.