Experimental Fitting Study On Arc-breaking Time And Arc Simulation Of High-power DC Relay Contacts

DC relay is an important component in DC control system.As electromagnetic relays tend to be high-power,long-life and high-reliability,their design is undoubtedly higher.Since the DC system does not have a natural zero-crossing point,the contact of the DC relay will inevitably generate an arc during the breaking process,causing problems such as erosion of the contact surface,excessive breaking time,or failure of the arc to extinguish,and the life of the switching device is generated.Great impact.In this paper,the effects of atmospheric physical parameters and magnetic field strength on the arcing time and the dynamic motion of the arc are analyzed in combination with experimental research and fitting simulation.It provides a theoretical basis for studying how to accelerate the arc extinguishing during the electromagnetic relay contact breaking process.In this paper,the electrical life experiments of CuMo85 contact in different atmospheric conditions are used to calculate the arc conductance value g under each current and voltage conditions and the average value of the arc breaking time of the contact in each atmosphere.Combined with the arc dynamic model formula of CASSIE and the experimental circuit equation,the arc time constant?under different conditions is calculated with the original data.The atmospheric property parameters are comprehensively considered,and the functional relationship between the arc time constant?,and the current voltage condition and?physical parameter is obtained.The theoretical arcing time of the untested voltage and current conditions and the ambient atmosphere are predicted.According to the calculation results of the theoretical arcing time,it can be concluded that the minimum arcing time in hydrogen is less than 0.01 milliseconds,and the order is H₂<SF₆<CO₂<N₂<Air<O₂<Ar.In this paper,the Cu contact is used in the two atmospheres:N₂ and CO₂,the DC voltage condition is 200-500V,and the resistive load current is 40-150A.The split-circuit experiment under different transverse magnetic induction is performed.The transverse magnetic induction intensity are 30mT.50mT,70mT,90mT,110mT,the breaking arcing time under each condition is calculated,and the functional relationship between the arcing time and current and voltage conditions and the magnetic induction intensity is fitted.It is concluded that with the increase of magnetic induction intensity The breaking arcing time shows a downward trend,and when the current reaches a large value,the magnetic blowing effect is more obvious.At the same time,the magnetic fluid dynamics model is used to model the electrical contacts using the large commercial software ANSYS Workbench and FLUENT.The temperature field changes of the arc arc column under static conditions and the current density distribution in the arc arc column are simulated finally,the coupling relationship between the temperature field,electric field and magnetic field of the arc is simulated.Finally,the results obtained by the fitting simulation are analyzed,and the calculated arcing time is compared with the arc breaking time of the experiment and the error is calculated.It is concluded that the calculated value of the arcing time of the knot is less than the experimental value.Under different conditions,the length and duration of the arc-breaking time are consistent with the experimental values,and the fitting simulation is reasonable.The simulation of the arc temperature field also conforms to the theoretical variation law.In summary,the influence of the magnetic field on the arc characteristics is from the macroscopic point of view,which affects the ampere force of the entire arc.From the microscopic point of view,it affects the J×B term of the momentum conservation equation in the magnetohydrodynamic equation,ie the magnitude of the magnetic density.,which in turn affects the entire motion of the arc.