Research On Magnetic Field Controlling Of Double-break Vacuum Circuit Breaker Arc

Double-break vacuum circuit breaker uses the superior insulation performance of short series vacuum gap, and avoids the saturated effect between breakdown voltage and vacuum gap under vacuum long gap. It is the developing trend applying to high voltage field instead of SF6 breaker, which has become a hot research topic in high electrical apparatus area in recent years. As the main factor affecting the performance of double-break vacuum circuit breaker, series vacuum gap arc also draws more and more attention from extensive researchers. Each series vacuum arc of double-break vacuum circuit breaker may have some differences from that of single-break vacuum breaker because of the asynchronism of switchers including the development process of the electric arc, the shape of the electric arc and so on. Especially the Non-uniform post of arc voltage distribution of series vacuum gap and the interaction between the arc have a great influence on double-break vacuum circuit breaker's performance. In this paper, in view of the related issues of series vacuum gap arc, the research method of using extra magnetic field is put forward. Double-break vacuum circuit breaker's arc is studied by adopting the combination of theoretical analysis, simulation and experiment method.First, in this paper, according to the forming mechanism and characteristics of vacuum arc, the influence of axial and transverse magnetic field produced by contacts and external magnetic field on the development and the shape of vacuum arc is analyzed, and the results with theory support on how magnetic field influence vacuum arc is obtained, which provides a reasonable and effective reference for magnetic field controlling of double-break vacuum circuit breaker.Through using the electromagnetic field analysis software, the magnetic field simulation of arc extinguish chamber with transverse magnetic field and axial magnetic field, the influence of paralleled type arrangement on double-break vacuum circuit breaker contact gap magnetic field, and also the influence of vacuum gap length and vacuum arcing chamber spacing on magnetic field distribution are analyzed. The results of how magnetic field affects vacuum arc are obtained under all kinds of simulation conditions.Through the combination of theoretical calculation and simulation analysis method, a magnetic field controlled system for double-break vacuum circuit breaker's arc experiment is designed. The system contains the magnetic field coil which can produce an adjustable magnetic field, the circuits controlling to produce different magnetic field and the controlling circuit of the magnetic field controlled system. This system can produce a magnetic field whose strength is 0?800mT and pulsewidth is 2.5?50ms, and it can meet the test requirements.Finally, on the basis of the 110kV/50kA synthetic test circuit, and selecting the double-break vacuum circuit breaker as sample switch, the arc which is produced by double-break vacuum circuit breaker when breaking short circuit current has been controlled using the magnetic field controlled system. The experimental results adjusting to the theoretical analysis and simulation results are obtained, and the best method of magnetic field control under different test conditions is putted forward. These conclusions also provide reasonable bases and references for the further research and design of double-break vacuum circuit breaker.