The Research and Optimum Design for Vacuum Circuit Breaker with Spring Mechanism

The contact welding phenomenon of the vacuum interrupter occurs frequently when the vacuum circuit breaker closing short circuit current. It cause the circuit breaker refused tripping or vacuum interrupter burst, which belongs to the serious accident. A lot of research work about contact welding phenomenon has been done in universities and companies at home and abroad. The reason in the vacuum interrupter contact welding after analysis can from different aspects: such as contact materials, closing speed, contact pressure, contact closing bounce etc. Phase selection can avoid the vacuum interrupter contact welding when it closes the bigger inrush current. But there have no research and optimize match about the institutions of the output characteristics and load characteristic, so as to improve the capability of anti fusion welding in the domestic and foreign reference. This article was based on test results, and put forward the output characteristic of the institutions and the load characteristics matching problem is another important influence factor of fusion welding, and analyzed the influence factors of the output characteristics of spring mechanism in vacuum circuit breaker. Finding that the output characteristics of vacuum circuit breaker are seriously affected by the track of the cam contour and the angles between four-bar linkage of driving mechanism. According to three different output characteristics, opening and closing test of short-circuit current respectively for vacuum circuit breaker, rated voltage: 40.5 kV, rated current: 31.5 kA, short-circuit close current: 80 kA. Contact spring pressure: 3200 N similar to 3400 N. Figure 1 shows the different four-bar linkage structures and output characteristics of the cam. Curve 1 for the four-bar rod Angle is alpha 1. 1 # cam structure, Curve 2 for the four-bar rod Angle is alpha 2, 1 # cam structure, Curve 3 for the four-bar rod Angle is alpha 2, 2# cam structure, spring mechanism relative to the output of the circuit breaker shaft torque curve. [GRAPHICS] To achieve a good match, the output of the organization characteristics and load characteristic of circuit breaker by optimizing the track of the cam and the transmission system of the angle between the four-bar linkage. According to the test results, the following conclusion are drawn : 1)As the contact change, the vacuum circuit breaker load characteristic and spring force with energy storage characteristic is opposite. To reduce force structure link in spring mechanism was adopted to realize the matching condition. 2)The four -bar linkage is better transmission structure, reduction of different a and the force reduction degree is different, the greater of the a and the better characteristic of the reduced force. 3)The cam is also a kind of effective force structure for reduction, and different cam contour track have different effect in force reduction, and the output efficiency of institutions is not the same. So it can realize the effective coordination of the output characteristics and load characteristic by trajectory optimization of cam contour. 4)It can be effectively to improve the capability of anti fusion welding when the circuit breaker close short circuit current by the effective match of the vacuum circuit breaker's output characteristics and load property of spring mechanism.