Robust optimisation of the spring actuator in a vacuum circuit breaker

We present a concept of robust optimisation design for the spring actuator in a 10 kV/12.5 kA vacuum circuit breaker. We assume the breaking and closing velocity characteristics, which are derived form the technical data of the interrupter, as the specifications for the problem, and take the lengths of the connecting rods of the actuator and the stiffness coefficients of the breaking and closing springs as the optimisation variables. The variance between the specifications and the velocities calculated at each breaking and closing point and the maximal variation allowed by the design variables within acceptable tolerances make up the multiple objective function. The optimal parameters for the spring actuator are given by solving a non-linear programming problem with multiple targets and two-level optimisation.