爆炸性环境电感分断建弧机理及影响因素

Arcing Mechanism and Influencing Factors on Inductor-disconnected-discharge in Explosive Environment

研究爆炸性环境电感分断放电建弧机理是解决本质安全型电感电路分断放电问题的有效手段,对推广应用本安型电气电子设备具有重要意义。基于IEC安全火花试验装置的电感分断放电宏观试验研究,发现极间电压快速跳跃到熔化电压,随后很快上升到最小建弧电压。因此,考虑极间场增强因子作用,建立甲烷–空气混合气体电感分断建弧过程的电子漂移扩散模型和非电子组分重物质输运模型,获得该建弧过程中各粒子密度、极间电势、电子温度、空间电荷和活性自由基粒子随时间的演变规律,揭示电感分断建弧机理及阴极鞘层形成机制;探究极间距离和外加电压对电感分断建弧过程的影响规律。数值模拟结果表明:空间内正电荷密度增大,引起电场畸变形成阴极鞘层;建弧过程产生的激发态N、O分子和—CH、—CH和H 3种自由基可促进电弧形成;外加电压低于15 V,且极间距接近甲烷–空气混合气体平均自由程或电子碰撞电离之前,极间距减小则不能维持电弧放电。

The study of inductor-disconnected-discharge(IDD) arc in an explosive environment is an effective means to solve the problem of intrinsically safe inductive circuit split-off discharge, which is of great significance to promotion and application of intrinsically electrical and electronic equipment. In the arcing process of the IDD based on the IEC safety spark test apparatus(IEC-SSTA), it is found that the inter-electrode voltage jumps quickly to the melting voltage, and then quickly rises to the minimum arc-building voltage. To reveal the arcing mechanism and the generating mechanism of the cathodic sheath, an electronic drift diffusion model and a non-electron component heavy material transport model are established to obtain the evolution laws of various particles, inter-electrode potential, electron temperature, space charge and active radicals in the CH-Air arcing progress.Numerical simulation results show that the density of positive charge in space increases, which causes electric field distortion to form a cathode sheath layer, and active radicals produced by arcing process, such as N, O, —CH,—CH, and H, can facilitate arc formation. The differential reduction of the pole spacing cannot maintain arc discharge until the additional voltage is less than 15 V, and the pole spacing is close to the average free range or electron collision ionization of CH-Air.