Research Of Economical Moulded Case Circuit Breaker

With further developement of urbanization reformation of China,the capacity of State Grid continues to increase,which cases the total market demanding of moulded case circuit breaker(MCCB),the main component in low-voltage distribution system,growing rapidly.MCCB,which is wildly used in low-voltage distribution system,is generally used for control and protection of distribution feeders,general switch of low-voltage side of small power distribution transformer,control and protection of power distribution terminal and residential power distribution terminal,and power switches of various production machines.In current situation,focusing on development of new MCCB with smaller size and higher performance meets the needs of reform of urban and rural power grid,which ensures the stability,safety and reliability of low voltage power-supply system,enables enterprises to maintain technological advantages in hot competition in the market of low-voltage electrical appliances,and promotes the marketing of other products of enterprises.Based on the project of HTS3 series MCCBs,focusing on MCCB HTS3-630 A,which has the highest rated current and the greatest difficulty on capacity lifting,this paper carry on analysis and research,and then expands to the whole HTS3 series.The research and design of this paper are as follows:Combined with the analysis of existing products in domestic and foreign markets and the development requirements of the project,the performance parameter and index of this series of products is set to meet the solution of the whole distribution system mostly,and to improve performance index while taking economy,practicality,safety,reliability of the products into account,rather than to pursue high targets blindly.After analyzing the performance parameters of the existing products home and abroad,it is decided to design MCCB HTS3-630 A as the same size of MCCB HTS2-400 A,so as to realizes the goal of rising capacity in a constant volume,saving materials,reducing costs and satisfying the economical requirements.In order to meet the volume designed and to achieve the necessary performance parameters,the temperature rise of circuit breakers will become a problem which needs to be conquered.Excessive temperature rise can cause adhesion of contact,the main heating element of MCCB,resulting a decrease in the electrical performance and the operation life of the circuit breaker,or even destroy it.It may cause fire,leading to property damage and casualties,if worse.To meet the requirement of the volume,it is needed to focus on the research of contact system and mechanism in design.We can obtain the design model of MCCB of HTS3-630 A series by designing and calculating the operating mechanism,contact system,copper bar and arc chute of MCCB HTS3-630 A.Simulation technology is used to verify the motion of the model which is often designed by virtual technology and the software ANSYS is used to proceed finite element analysis of the temperature rise of the main heating element(contact).After verifying the model by simulation,we can obtain a correct model which could be made as the prototype of MCCB HTS3-630 A and then operating mechanism experiment,electrical life experiment,breaking experiment and temperature rising experiment are tested to verify the correction of simulation.With concise appearance,economical price,and proper technical indicators,this series of circuit breaker,would be welcomed by customers and accepted by market,thus will has a broad development prospects in the near future.