Study On Characteristics Of Vacuum Switching Are In The Post-Arc Stage

Vacuum circuit breakers are control and protection equipment in power system.With the advantages of easy to maintain,small volume,long service life,light quality,suitable for frequent operation,vacuum circuit breakers have been applied in power state widely.With the continuous improvement of manufacturing technology and theory research level,vacuum circuit breakers are moving in the direction of high voltage,large current,miniaturization and intelligence.It is a hot issue that Vacuum circuit breakers can successfully break without reigniting which is the key to solve the problem by further studying on arc characteristics.The characteristic changes of arc in combustion process have an important influence on the comprehensive characteristics of vacuum circuit breakers,in which the arc characteristics in the post-arc stage play a decisive role.In this paper,arc characteristics in the post-arc stage are mainly studied.A high speed CMOS camera was used to photograph the sequence images of arc in the post-arc stage and image processing technology was used to extract the geometry features of arc such as perimeter and area.In order to analyze its characteristics,the effects of different voltage and gap on the arc area were studied,and the diffusion rate of the area in the post-arc stage was studied.The dielectric recovery strength plays an important role in the post-arc stage.In this paper the influencing factors of the dielectric recovery strength including contact materials,metal vapor density,breaking current and geometric size of the electrodes are explored.The feature extraction of cathode spots has been carried out in this paper.The area of circular target was obtained in the end mainly through boundary extraction the round target,so the research of vacuum switching arc in the post-arc stage got further promoted.A GUI.interface was developed to study the arc characteristics of post-arc stage by MATLAB.The main features include image denoising,image enhancement,edge detaction,arc area and arc perimeter extracted and so on.Arc resignation has been introduced in the end of this paper and a method to determine the reigniting was designed.The work in the thesis is expected to study the arc characteristics of post-arc stage in depth,in order to further study the mechanism of the dielectric recovery strength and reigniting.