中文摘要：

为研究IEC安全火花试验装置短路放电的击穿放电机制,针对室温1atm下不同浓度的甲烷空气混合气体,对几百微米~几毫米范围内的击穿实验进行了设计。分析表明对于不同浓度甲烷空气混合气体,击穿电压与电极间距的关系曲线均呈现马鞍形;室温1atm下8.5%甲烷空气混合气体在几百微米~几毫米间隙范围内的最低击穿电压表明试验装置的电容短路放电过程在巴申定律的适用范围之外且其临界击穿间距在几百微米以下。可见,该放电过程中间隙内的碰撞电离效应并不突出,阴极电子发射是其击穿放电的主导机制,该放电过程类似真空放电,通过安全火花试验装置得出不同介质环境的电容电路短路放电波形对此进行了验证。

英文摘要：

Aiming at the methane-air mixtures at room temperature and one bar pressure,the breakdown tests in500μm ~ 5mm range of clearance have been performed to study the effect of gas dielectric on the breakdown of short circuit discharge with the IEC safety spark test apparatus（ IEC-SSTA）. The experimental results show that the relationship between the breakdown voltage and gap distance fits to the typical gas-breakdown chart with changing the methane-air mixtures. For 8. 5% methane-air mixtures,the lowest voltage is about 300 v which is far larger than the operation voltage of the test circuits with IEC-SSTA. It is also shown that the discharge process does not belong to the category of gas discharge,and the effect of gas dielectric on the breakdown of the gap can be ignored. It is pointed out that the discharge process can be categorized into vacuum discharge rather than gas discharge,and the dominant breakdown mechanism of the discharge is the cathode electron emission. Short circuit discharge experiments of capacitive circuit in different media environment with the IEC-SSTA are performed,The experiment results are in good agreement with the analysis showing the feasibility of the proposed methods.