Research Of Novel Double-break Miniature Circuit Breakers With Selective Protection

With the development of national economy and the increase of people's livingstandards, increasing of electrical devices and branch circuits in low voltage system,the application of selective circuit breaker is more and more attention by people. Interminal power distribution system, the main and branch of the circuit breaker isgenerally adopt energy selection cascaded techniques. But this way can realize partialdiscrimination, when the short circuit current to a certain extent, upper and lowerstages at the same time or overstep tripping phenomenon is relatively common, whichaffect the reliability and continuity of power supply system, and even affect the safetyof the user. So the circuit breaker in terminal distribution system should have the fullcurrent selective protection function. In recent years, some domestic and foreignenterprise dedicated to the research and development of miniature circuit breakerswith selective protection, and achieved certain results. However, the new generationof technology has some defects and market restrictions, needs further research fortechnology and marketing.This thesis has carried on the analysis to the present domestic and foreigntechnology and development status, Introduced the working principle andrequirements of the selective protection of miniature circuit breaker, and the defects ofthe existing technology. Proposed the research content and framework new model ofselective protection of miniature circuit breaker.This thesis studied on double breakers technology, operating mechanism, doublecircuit mechanism, current limiting technology, electromagnetic repulsive forceconverting mechanism technology etc., and designed a new type double breakers withselective protection of miniature circuit breaker. This breakers have the followingfeatures, that are multi control input and output can be achieved with the designedoperating mechanism, the automatic closing contact device with rotary doublebreakers, the permanent magnet technology design of electromagnetic tripping device,and an arc extinguishing system with strong effect of magnetic and air blowing. By using the comprehensive field analysis software ANSYS and multi-bodydynamics software ADAMS, the scheme of operating mechanism and electromagnetictripper are designed. According to the analyzed simulation results, an optimizedscheme is made to perfect the operating time of the mechanism and the dynamiccharacteristic of electromagnetic tripping device, by doing this, the needs of theselective protection of this circuit breaker would be satisfied much better. Key projectof this circuit breaker was tested, and further comparisons of different design schemeand optimized scheme were made to fulfill the expected performance of the circuitbreaker.A brief summary is included in the last section of the paper, also the developmentof selective protection technology and further study of the circuit breaker areprospected.