Design of Bistable Permanent Magnet-Repeat Mechanism for Medium Voltage DC High Speed Switch

Abstract

The repulsive mechanism has the advantages of short response time, fast opening speed and simple structure, and fully matches the short circuit breaking of the DC system to quickly establish the insulation gap, widely used in medium voltage DC circuit breakers. In this paper, a bistable permanent magnet repulsive mechanism of 10kV DC circuit breaker is proposed. The magnetostatic research is carried out for the permanent magnet holding mechanism and the repulsive mechanism, and based on the research results, the experimental prototype is built and the prototype experiment is completed. The reliability of the function of bistable permanent magnet repulsion mechanism is verified by the experiment. According to the breaking demand of 10kV DC circuit breaker, the overall design scheme of a bistable permanent magnet repulsive mechanism is proposed. According to the theory of electromagnetic field, the magnetostatic model and dynamic model of the permanent magnet mechanism are built. The influence of key structural parameters on the static retention characteristics is studied, and the structural parameters of the permanent magnet mechanism are determined. Based on the parameters calculated by the simulation, an experimental prototype of the bistable permanent magnet repulsive mechanism is built. The experimental scheme of the rated opening test and the rapid opening test is designed, and the prototype rated breaking curve, the quick opening response time curve and the quick opening characteristic curve are obtained. Comparing the experimental results with the requirements of the circuit breaker, the breaking characteristics of the repulsive mechanism can meet the two breaking requirements of the rated breaking and short-circuit breaking of the circuit breaker, and verify the feasibility of the prototype of the repulsive mechanism. The simulation results and experimental results verify the accuracy and practicability of the simulation model within an acceptable error range.