Analysis Of Stress Distribution In Fault State Of High Voltage Circuit Breaker Spring Operating Mechanism

High voltage circuit breaker,as an important device for protection and control of electrical circuit interruption in high voltage electrical equipment,is an essential element in power distribution system of power plants and substations.Once it has a failure or an accident,it will cause inestimable economic loss and social impact.A large number of accident investigation and statistics of circuit breakers show that the mechanical failure of the operating mechanism accounts for more than half of the failure of the circuit breaker.The reliability of the whole circuit breaker is not only related to its electrical performance such as interruption and insulation performa nce,but also to the mechanical reliability of the operation mechanism such as operation characteristics,mechanical strength and so on.This paper firstly describes the characteristics of SF6,and the structure and principle of high voltage circuit breaker.the use of Pro/E three-dimensional model of operating mechanism of the original spring,using the finite element software HyperMesh,the 3D model of various mechanical fault condition of the finite element model of circuit breaker spring operating mechanism of lever roller wear,crack,fracture of pin,rotation vice card and closing spring fatigue and a series of mechanical failure is calculated by simulation.using the LS-Dyna stress,the spring operating mechanism of each failure under the key parts of the stress distribution and the maximum stress position.At last,the stress collection test was carried out on the key parts of the operating mechanism by using the strain gauge.By comparing the simulation results and the experimental results,it shows that cam and roller mechanism has large impact force,crank arm,drive rod and spring components are stress concentration,and,with the number of operations increases,the circuit breaker is very easy to appear the phenomenon of fatigue,when the fatigue cycles reach a certain value.There will be wear,crack and even fracture and a series of phenomena.At the same time,there are still problems of vibration and instability of long rod parts.The analysis method and results of this paper can provide theoretical guidance for the research and optimization design of circuit breaker’s operation mechanism,and provide a useful reference for failure analysis and reliability design of circuit breaker’s spring operation mechanism.