Investigations On The Characteristics Of Arc Forms And Diagnosis Of Plasma Parameters In VCB

As one of the controlling and protecting devices in modern power system, VCBs have several advantages over other switches; nowadays they have been widely applied in industries and agricultures with the rapid development of power supply market, accounting for over 80 percent in China. VCB with multiple breaks and synchronous switching have become important developing of VCB, their common technical problem is researches on the related theory of vacuum arc in short-gap and its controlling regularity, which is the research object in this paper. Arc forms are external important characteristics of vacuum arc while plasma parameters are the internal important characteristics. Controlling on the change regularity of external and internal characteristics has been become an important field in vacuum arc. Researches on the forms of vacuum arc using high-speed digital camera CMOS and diagnosis of plasma parameters based on digital image processing CCD are put in this paper, and all these point out the direction of the further study of controlling theory.Application of digital image process is absolutely necessary to get information characteristics of vacuum arc form images. Firstly, image format and image precision are reviewed; secondly vacuum arc images are noisily filtered using median filter; histogram equalization is applied to enhancing details and maximizing the information content of the arc images; the edge points of the arc images have been detected using Canny operator; the images geometric characteristic and their perimeter are analyzed; and images gray contour line and their pseudo-color display are shown. At last, all these can provide some theoretic of capturing the information from vacuum arc images.To do researches on the form characteristics of vacuum arc, in this paper, combined with the vacuum chamber model, experimental set-up is designed to do researches on the characteristics of vacuum arc, including a de-mounted stainless steels chamber with two glass windows, high arc current which is supplied by C through L at a frequency adjusted to about 50Hz and measurement of voltage-ampere etc. A high-speed image collecting system using CMOS digital camera is arranged. Using this system, the whole igniting process of vacuum arc is researched and analyzed. Axial area spreading speed of vacuum arc is put forward in the end. The effect of gap distance, voltage degree between the captor and axial magnetic on the axial area change are analyzed in particular. In order to get the vacuum arc parameters from the images information, an arc parameters diagnostic system using high-resolution digital CCD camera is designed too. A diagnostic mathematical model on plasma parameters is built based on principle of temperature radiation measurement, combined with Abel inversion; radial distribution of electron density and temperature distribution are diagnosed.In the end, in order to prove the feasibility of the optical method, the plasma parameters are measured using Langmuir probe. Comparative and analytic researches on the results are got by three different ways.The aim of these researches is to improve the work performance and reliability of switching devices and finish the protection and control of the power supply system. This work is based on the design of VCB with multiple breaks and vacuum arc of high current in short-gap is studied. It is one part of the key-project of NSFC:"Arc plasma adjusting and controlling in metal vapor and its applications in the field of high voltage circuit breakers" (No.50537010). The related theoretical researches on the form characteristics and plasma parameters of vacuum switching arc are taken in this dissertation, some experimental basis for vacuum arc controlling theory have been put forward.