Molded Case Circuit Breaker Electric Contact Erosion and Design for Reliability
In the 2014 ICREPEC, contact welding of 35Ag65W contacts with several variations in tungsten particle sizes and Ag rich layer were compared in their welding force on a model switch.The physics of failure in contact welding was analyzed by (a) Weibull Analysis method to quantify the weld force (stress) of various contact material parameters, and (b) to design the suitable opening force (strength) so that the reliability of no contact welding failure can be estimated.In continuation of that research, the contact constriction resistance as a function of contact force is measured on many new and eroded contact pairs to show the effects of switching arc erosion.It can be shown that the constriction resistance is very much dependent on contact force.This is used to show the importance of understanding the concept of required contact force, designed force and end-of-life force.An adequate or good contact force in the circuit breaker is dependent on the proper understanding of several contact degradation mechanisms.The end of life reduction of contact force can be due to a variety of factors such as contact erosion resulting in thickness reduction, accumulation of arc erosion oxides, stress relaxation of spring and bimetal, drying of lubricants, contamination from external sources, and deposition of erosion debris on the moving joints.This is to highlight the importance of a good understanding of contact material properties, electrical test parameters and device parameters.
contact circuit breaker resistance heat rise
Chi H.Leung
Electric Contact Material Consultant Export, Pennsylvania, USA
国际会议
江苏常熟
英文
6-10
2017-04-18（万方平台首次上网日期，不代表论文的发表时间）