On the dynamics of spring-type operating mechanism for 69 KV SF₆ gas insulated circuit breaker in open operation

This paper investigates the dynamic response of a spring-type operating mechanism of a SF₆ gas insulated circuit breaker in open operation. For a single degree-of-freedom rigid mechanical system subjected to external forces, its motion can be represented by a second order non-linear differential equation. In this paper, the vector-loop method is employed to derive the kinematic coefficients of all the members of the spring-type operating mechanism and their centres of gravity. The equation of motion is then solved using the fourth order Runge-Kutta method. The analytical results revealed that the breaking time of the circuit breaker was 0.078 s, a mere 5% difference from the experimental result. The dynamic response of the circuit breaker with different spring constants was studied and its effect on the breaking time was also assessed. With the dynamic response known, the input driving torque of the circuit breaker can also be computed from the equation of motion.