| Moulded case circuit breaker(MCCB)is an important electric device in the low-voltage power supply and distribution system,which has presented the trend of miniaturization,intelligence,high performance and modularization.The operating mechanism of MCCB should ensure the targets of the performance,including opening range,overrun,contact pressure and others.However,the intercoupling of various performance,indexes and structure parameters results in difficulty of the design and optimization of operating mechanism.And due to a rigid-flexible coupling mechanism with spring,there is theoretical significance in the analysis of motion states and simulation solution of kinematics and dynamics of the new operating mechanism.Based on the mechanism synthesis and analysis methods,a new MCCB operating mechanism with upper fixed contact is designed.The motion states,kinematics,dynamics,performance simulation and experiment device are studied,which will provide the important practical value for the design of new MCCB operating mechanism.The main contents are as follows:(1)A new MCCB operating mechanism with upper fixed contact is proposed.Based on the research on the working principle of MCCB and basic structure of operating mechanism,a new MCCB operating mechanism with upper fixed contact is designed using mechanism synthesis and analysis methods,which contributes to increasing the breaking velocity and improving the breaking capacity of MCCB.(2)The rules of dividing motion phases of new operating mechanism with upper fixed contact are proposed.Based on singular configurations and contact states between stoppers and mechanism,seven motion phases of the closing and opening and tripping operation of MCCB are divided.The motion states of key parts and operating mechanism in different phase are analyzed.(3)The offset rules of the second singular configuration of new operating mechanism with upper fixed contact are revealed.The necessary condition of operating mechanism completing the closing operation is obtained by statics analysis.Based on the vector-loop equations and lagrange equations,the kinematic and dynamic model of tripping operation are built,and a calculation model of breaking velocity is obtained.The offset rules of the second singular configuration are revealed based on the kinematic and dynamic model of closing operation and validated by simulation in Adams software.Appropriate ranges of spring parameters are determined according to the offset of the second singular configuration,ensuring closing position consistency of MCCB operating mechanism.(4)Structure design and performance simulation of new operating mechanism with upper fixed contact are completed and experiment device for testing tripping time is built.According to the design parameters of MCCB,motion states and dynamic model of operating mechanism,the structure design of key parts is completed and the 3D model of operating mechanism is built.The main performance of new MCCB is simulated in Adams.A experiment device for testing breaking time is designed,which will provide support to test breaking time of new MCCB. |
