The objective of this paper is to propose a design method to optimize the closing cam of a high-voltage vacuum circuit breaker approaching the minimum arcing time. First

the optimum closing speed characteristics are determined through experiments. The function of the prestrike closing velocity and the total arcing duration is obtained

which indicates that the closing time of a 126 kV vacuum circuit breaker is the minimum when the pre-breakdown speed is 1.15 m/s. Next

the cam profile is determined by the closing curve obtained. According to the closing curve of the vacuum circuit breaker

one can determine the rotation angle of the spring operating mechanism main shaft corresponding to each point on the curve. The energy storage shaft rotation angle is determined according to the energy required for the closing spring. Then

the cam profile is determined according to the ratio of the main shaft rotation angle and energy storage shaft rotation angle. Finally

a cam design software is developed according to the cam profile design method. The simulation results by ADAMS simulation software show that the pre-breakdown speed is 1.18 m/s

which indicates that the design perfectly satisfy the demands.