Voltage Distribution Uniformity Design And Optimization Of Multi-Break Vacuum Circuit Breaker

Vacuum circuit breaker is widely used in medium voltage for its advantages of long service, good safety etc. Considering the environmental protection point, the researchers try to develop vacuum circuit breaker to higher voltage grade. So the SF6can be not commonly used. However, the increase of contact gap causes the saturation characteristics of insulation strength between the contacts, which limits the development of single vacuum circuit breaker to higher voltage grade. Compared with increasing the gap length of single vacuum circuit breaker, multi-break vacuum circuit breaker is more reasonable. Currently, the voltage distribution uniformity of vacuum arcing chambers is a critical issue in the development of multi-break vacuum circuit breaker. The main content of this paper is how to improve the breaking capacity of multi-break vacuum circuit breaker by improving the voltage distribution uniformity of different vacuum arcing chambers.At first, this paper explains the existing of grading capacitor is the reason why voltage distribution of vacuum arcing chamber is not uniform by introducing the mechanism of transient recovery voltage distribution and the equivalent circuit. And the circuits for calculating equivalent capacitors of double-break vacuum breaker and triple-break vacuum breaker are introduced, which is the theoretical basis of simulation.The models of multi-break vacuum circuit breaker are built, then the voltage distribution of models in different arrangements and the equivalent capacitors are calculated. The effect of contact gap on voltage distribution of double-break vacuum circuit breaker is analyzed. It is confirmed that the voltage distribution is more uniform by the way of adding equalizing capacitors and changing contact opening distance.Then, the result of simulation is verified by experiments. The testing results of voltage distribution with different equalizing capacitors are compared to check the improving of voltage distribution uniformity, and the effect on voltage distribution uniformity of changing contact opening distance is verified by the experiment of transient recovery voltage distribution.At last, the design of improving voltage distribution uniformity of two vacuum arcing chambers by choosing reasonable arrangement, adding equalizing capacitor and changing contact opening distance is applied to the production. A design scheme of126kV high voltage double-break vacuum breaker is proposed.