Design of Dual Motion Mechanism Moving along Optimized Stroke Curve to Improve Capacitive Current Switching Performance for Gas Circuit Breaker

This paper presents the design of a dual motion mechanism for a high-voltage gas circuit breaker to give good capacitive current switching (CCS) when high voltage is applied during the half cycle from contact separation. The dual motion system drives two electrodes in opposite directions from one other, which reduces the operating energy because of shortening the movable-side stroke. To achieve high CCS performance with a lower operating energy, a fixed-side arc electrode requires quick operation in the CCS period with a short stroke. A driven-side stroke expressed with an arbitrarily shaped speed curve is proposed to increase the withstand voltage during the period for CCS and decrease the load acting on the dual motion mechanism. The dual motion mechanism is composed of two arbitrary-shaped grooved cams that cross each other. A pin positioned at the intersection point of the grooved cams rotates a lever linked to both electrodes while changing the lever ratio that shortens the path length of the pin movement. A dual motion mechanism having the optimal shape was manufactured, and the stroke curve was measured. The measured stroke curve was in good agreement with the ideal stroke characteristics.