Simulation On 12kV1250A Switch Tulip Contact With Memory Alloy Gaskets

With the wide use and continuous development of vacuum circuit breaker,more and more attention about the problem of vacuum circuit breaker's heat has been attracted by vacuum circuit breaker research experts both at home and abroad.When the equipment is in long-term operation,switch tulip contact and cabinet fixed contact of vacuum circuit breaker in switch cubicle emits heat because of oxidation and large contact resistance,resulting in failure of contact heat and temperature rise,this phenomenon has become common problem which occurred in the use of switch cubicle.What's more,overheating is a process of constant development,overheat degree will increase and generate big influence in the performance of insulation parts and equipment life without control.Shape memory alloy is a new functional material which has shape memory effect,can sense outside temperature,and produce shape displacement after heating temperature,which generate restoring force when displacement is limited.The application of tabletting made of memory alloy material in switch tulip contact of circuit breaker,when high temperature of contact caused by improper operation,long-term running,and aging,the memory alloy tabletting reacts pressure temperature variation,get back into shape,increase binding force on the top of contact,and then increase the land area of contact,reduce contact resistance,thereby lowering the temperature rise on the top of contact,enhance the safety performance of breaker,and avoid temperature rise fault caused by abnormal heat of contact.Based on temperature sensitivity of memory alloy materials,the paper employed fem simulative analysis technology to make simulated analysis of the temperature field of vacuum switch cabinet which used memory alloy,and provide reference for simulated validation memory alloy lowering the effect of temperature rise of switch cubicle.The main research work and conclusions are as follows:Chapter One: expound research background,current situation,content and meaning of the thesis.Analyze main factors which caused temperature rise of vacuum switch cubicle,and put forward main ideas and research content of this thesis on the basis of research status of temperature field simulated analysis of switch cubicle.Chapter Two: elaborate contact resistance theory,heat transfer theory and mechanics theory.Chapter Three: analyze characteristics,research status and main application of memory alloy material,and research restoring force and temperature test process of memory alloy tabletting,and obtain test data.Chapter Four: use microcomputer constant temperature testing machine to heat switch tulip contact through establishing different test platform,employ loop resistance tester measuring contact resistance under different combinations of memory alloy tabletting with ordinary metal tabletting to obtain optimal combination,and verify optimal combination by simulation.Chapter Five: carry on test and simulation of two contact anomalies of fixed contact,and respectively analyze the influence of two cases on safety performance of switch tulip contact.Chapter Six: conduct temperature rise test of switch tulip contact,and respectively simulate the three different kinds of boundary conditions,find out simulation method which has minimum error of test results through analysis of temperature field simulation results,and then further predict several different situations with insertion depth through simulation.Chapter Seven: stimulate whole temperature field of switch cubicle,and adjust the accuracy of simulation model according to test,comparatively analyze the effect that memory alloy materials applied in vacuum switch cubicle with 12 kV1250 A to reduce temperature rise on this basis.