A vacuum circuit breaker’ s closing speed depends on the matching degree between its load characteristics and the output characteristics of the spring operating mechanism if the linkage mechanism and the vacuum interrupter transmission system

which are located between operating mechanism and vacuum interrupter

have been determined

while the matching degree depends on the cam profile.This study conducts optimization design of the cam.The cam profile consists of four arcs.The output torque of the cam can match the load torque

and satisfactory output shaft angle and closing speed can be obtained by changing the center position

radius and circumferential angle of each arc.For a spring operating mechanism used in 12 kV dry air insulated circuit breaker

the cams are optimized considering low

medium and high average closing speed

respectively.A virtual prototype of circuit breaker is built in Adams

and three different optimized cams are imported into the virtual prototype for simulation analysis and comparison.The results show that the cam optimization method in this paper is effective

and the cam which is optimized for medium closing speed well balance reliability and closing power of the operating mechanism.