Research On Effection Of Arc Transport Properties For SF₆Circuit Breaker

The metal vapor is formed with contacts erosioned in the breaking process of circuitbreaker, makes a certain effect on the arc transport properties. For describing the dynamicvariations of the metal vapor plasma and the influence on the electric field distribution inarc quenching chamber during the breaking process of the circuit breaker, investigation onthe transport properties of metal vapor becomes the key to study the microscopic model.Foranalyzing the variation of arc transport properties with temperature and pressure,aEindhoven micro arc model has been used in this thesis. Based on the solution and analysesof thermal dynamics equilibrium and Boltzmann equation model, the variation of transportproperties with the temperature and the pressure and particle number density has beenobtained, the quantitative description of electrical conductivity and thermal conductivityhave been achieved.Based on Eindhoven micro arc model that satisfies the law of massaction, charge quasi neutral conditions,balance of stoichiometric thermal equilibriumcondition constraint conditions,a micro-arc plasma model of SF₆mixed metal vapor arcplasma has been established.Based on the plasma chemical formation mechanism andthermodynamic equilibrium,the variations of electrical conductivity and thermalconductivity in different opening strokes have been obtained.Arc electrical conductivity and thermal conductivity in the arc exist in the process ofhistory, are changing dynamically with the function of temperature, pressure and particlenumber density and other parameters.With different composition of metal vapor,thevariations of arc transport properties are different.Since the flow field in SF₆circuit breakeris variable boundary problem with compressible,unsteady,viscous,active andsupersonic.The spatial distribution of flow parameter based on the numerical simulation ofgas flow field with compressible viscous boundary in interrupter has beenobtained.According to the distribution of flow parameter in the arc quenching chamber byusing interpolation method,the spacial distribution of electrical conductivity and thermalconductivity under different opening strokes has been obtained,and the arc area has been analyzed according to the arc transport properties.According to the characteristics of thecharged particles and metal vapor, based on Maxwell equations of the electrical field of thearc quenching with different metal vapor has been analyzed by using the finite elementnumerical method and the description of the the distribution of electrical field has beenobtained.