Study On The Reliabilityand Optimum Design Of Low-Voltage Circuit Breaker Operating Mechanism

Low-voltage circuit breakers is an important member of low-voltage electrical apparatus. With the improvement of the automation level, the demands of the circuit breakers product performance and life have become improved. The reliability of circuit breakers is mostly dependent on the performance of operating mechanism. It's significant and useful that study on the reliability and optimum design of low-voltage circuit breaker operating mechanism.Focusing on CM1-225 Molded Case Circuit Breaker, this paper studied the break-brake process, reliability analysis and optimization design of the circuit breaker operating mechanism. The three-dimensional model of MCCB was established based on the PRO / E software and three dimensional measuring machines, and then assemble the part each other with the PRO/E software. The model was imported to ADAMS through interface software. After a preliminary analysis, the model was refined with the actual parameters.Based on the stress - strength interference model,this paper studied the reliability analysis methods of the circuit breaker operating mechanism.The rigid-flexible coupling model of operating mechanism was setting up through the modeling agencies of ADAMS flexible body. Simulation analysis shows the stress value changes and distribution on the key components of operating mechanism. Combined the reliability design theory with simulation data, the static strength and fatigue reliability of relevant parts was obtained.Based on the model, the effect of different factors on operating velocity of mechanism was analyzed ,which include spring stiffness, axis position of key components of operating mechanism and structure of parts .The result of analysis got the factors of impacting on the speed of opening. This paper, which defined design variables, optimized the operating mechanism aim at improving breaking capacity.This project is supported by Natural Science Foundation of Hebei Province"The Reliability Theory and Network Technology of Electric Power System Protection Apparatus Analysis and Its Application".