Abstract: The motor actuator used in circuit breaker has the advantages of simple structure，small dispersal of

action and strong controllability，which provides the possibility for the switch contact of circuit breaker to follow

the preset reference curve. The traditional control method can not adjust the parameters according to the movement process of circuit breaker switch contact，and the following is poor，and the intelligent control algorithm is complicated in calculation，affects the rapidity of control system，and is extremely difficult to implement in engineering. A piecewise pseudo-differential control strategy was presented，which avoids direct differentiation of the controlled variables and has the ability of fast dynamic response and anti-interference. Meanwhile，the control system parameters were given according to the segmented environment to ensure the following accuracy. The control strategy model was established for simulation analysis，and the 126 kV circuit breaker motor actuator control system was developed for experimental verification. The simulation and experimental results show the effectiveness of the control strategy.

      Key words: vacuum circuit breaker （VCB）；motor actuator；piecewise control；control algorithm