开关柜内部故障电弧产生压力冲击的辐射模型

Radiation model for pressure impact caused by the internal fault arc in switchgear

基于磁流体动力学法研究了开关柜内空气故障电弧的辐射模型。采用净辐射系数(NEC)法、半经验NEC和P1三个辐射模型,计算了密闭开关柜内部空气故障电弧的辐射传递过程和压力冲击效应。通过将三个模型计算的压力上升和试验结果进行比较,确定了适于故障电弧计算的辐射模型。重点分析了半经验NEC模型中重吸收层的起始温度边界对压力上升的影响。结果表明低温区域的重吸收效应严重影响故障电弧的能量输运,进而影响内部压力上升。和NEC模型相比,P1模型和半经验NEC由于考虑了重吸收效应更适合于故障电弧的压力计算。采用P1和0.7<α<0.83的半经验NEC模型(α为重吸收区域的起始温度边界的可调参数)所计算的压力上升更接近于试验结果。

The radiation model of fault arc in a closed air switch gear is investigated by using magneto-hydrodynamic method.The net emission coefficient(NEC),semi-empirical based on NEC as well as P1 model are employed to calculate the radiation transport and pressure impact of fault arc in the closed air switch gear.By comparing the calculated pressure rises which based on the three models with the experimental results,the radiation model applicable to fault arc calculation is determined.In particular,the influence of the initial temperature boundary of the re-absorption layer on the pressure rise in the semi-empirical NEC model is analyzed.It has been found that the re-absorption effect in the low-temperature region influences the energy transport of fault arcs seriously,and hence the internal pressure rises.In comparison to NEC model,P1 and the semi-empirical model with 0.7<α<0.83 are more applicable to the pressure calculation of fault arc,whereαis an adjusted parameter of the starting temperature of the re-absorption layer in the semi-empirical model.