Research Of Dynamic Characteristics And Behavior Of DC Switch Arc Under Axial Magnetic Field

As an key component of the power system,the switching device is widely used in various fields and sectors of the national economy and the country,and its reliability is crucial.For the switching device with contacts,an arc is unavoidably generated during the breaking process,and the generation of arc may delay the circuit breaking or even burn the contacts and destroy the insulation.The derivatization mechanism and development law of arc are the research hotspots and difficulties that researchers at home and abroad are generally concerned about.Compared with alternating current arcs,there is no natural zero-crossing phenomenon in DC arcs,and it is more difficult to break them.Using a magnetic field to break the arc is an effective way to cut off the line quickly.Therefore,it is very important to deeply study the effect of magnetic field on the DC arc characteristics of low-voltage switch device.In this paper,the influence of magnetic field on switching arc characteristics is analyzed by experiment and simulation.A DC arc experimental platform based on high-speed photography and speed regulation of impact contacts is designed.A high-speed camera was used to capture the arc image in the contact breaking process of the experimental prototype.The arc voltage and current waveforms are collected using the detection platform.Based on the experimental platform,the contact breaking speed,breaking current and the effects of different axial magnetic fields on arc behaviors,arcing time,arc root location,arc shape and electrical corrosion characteristics of contacts are studied.Based on the experimental model and the drift diffusion equation of gas dynamics and the Poisson equation calculated by the coupling electric field,the mathematical model of the arc under the micro simulation of magnetic field is established.The non-equilibrium process of the arc plasma formation under the action of the magnetic field,from the break of the contact,after the liquid metal bridge breaks,the pole is filled with a large number of gas charged particles to the arc plasma has be simulated.The influence of different magnetic field intensity on the microcosmic arc parameters such as field strength,space charge density and pre-arc radius of arc plasma sheath is analyzed.The research results can provide theoretical basis for the application of axial magnetic field arc blowing technology in the design of arc extinguishing system for switchgear.