Diagnosis Of Arc Shape On VCB And Model Visualization

In view of its small volume,long life,high reliability and frequent operation,VCB(vacuum circuit breaker)is widely used in transmission and distribution systems with middle voltage.With the increasing of voltage level in transmission line,VCB which used in high voltage and current has already become an irresistible trend.The vacuum-insulating medium causes a smaller separation,faster action,shorter duration,compared with gas medium.Arc shape affects or even determines the performance of arc-extinguishing and dielectric recovery directly.Different designs of vacuum extinction chamber will produce different arc shapes,and through their diagnosis,we can build a connection between breaking capacity and arc shape.Therefore,the study of arc shape plays a key role in the process towards large capacity.In this paper,the digital images of vacuum arc were collected.Using image processing and feature recognition,the morphologic changes in various arcing stages were analyzed qualitatively,and the location data of arc shape were counted.At last,the relationship between arc shape and breaking capacity was described from vacuum plasma perspective which going through the formation,development and diffusion process.According to applications of VCB in different areas,the current situation and development trend of VCB were introduced,the influence factors were analyzed,such as electrode voltage,short-circuit current,external magnetic field,contact gap,contact size and material,and the two main diagnosis methods were discussed:probe method and spectroscopic method.In this paper,the working principle of trigger circuit which used in arc igniting was analyzed,and the working characteristics of CCD and CMOS sensors were introduced in experiment.According to 464 arc-image frames,the formation process of arc plasma was described,and the evolution shapes in different stages were provided.The research was focus on description method of texture characteristic,geometry form and contracted state of vacuum arc.According to the results of electromagnetic field simulation,the fundamental causes of arc changes were explained.The 2D visual model was drawn by collecting arc shape data,the evolution process was demonstrated from arc starting,arc burning and arc extinguishing aspects,and the graphical user interface was created.The 2D model was identical with real arc,and could become a criterion on breaking performance of VCB.