GIS中S_2OF_(10)作为局部放电特征气体的有效性分析

Validity Analysis of S_2OF_(10) as a Target Gas of Partial Discharge in GIS

局部放电监测是实现气体绝缘组合电器(gas insulated switchgear,GIS)缺陷预警的重要依据和手段。DL/T639—1997《六氟化硫电气设备运行、试验及检修人员安全防护细则》等化学诊断法规程将S_2OF_(10)作为一种GIS局部放电特征气体列入常规检测范围。为探究S_2OF_(10)作为局部放电特征气体的有效性,在110k V GIS试验平台上设置典型放电模型,研究不同放电类型和放电程度下S_2OF_(10)随时间的变化规律,并通过B3P86/6-31G(d,p)量子化学计算揭示了S_2OF_(10)的生成机理。试验和理论计算均表明,S_2OF_(10)由自由基SF5、SF5O结合生成,放电状态下只有极少量的SF5、SF5O生成,且二者共存机会很小,GIS内不同放电类型和能量条件下,S_2OF_(10)均不会大量生成。结合对运行GIS放电气室气体组分分析结果,S_2OF_(10)不能作为一种有效的局部放电特征气体用于GIS潜伏性缺陷诊断。

Partial discharge monitoring is an important basis and means to achieve defect warning of gas insulated switchgear（GIS）. According to DL/T639—1997 ＂Safety and protection rules for the operation, test and maintenance personnel of SF6 in electrical apparatus＂ and related standards of chemical diagnosis method, S_2OF_（10） has been identified as one of the target gases of partial discharge in GIS. To explore the validity of S_2OF_（10） as a target gas assessing partial discharge in GIS, typical PD patterns were set up on 110 k V GIS experiment platform, studying the variation of decomposition product S_2OF_（10） at different discharge level over time. Meanwhile, B3P86/6-31G（d,p）, a method of calculation based on quantum chemistry, was adopted to explore the generation mechanisms of S_2OF_（10）. Experiments and theoretical calculations show that S_2OF_（10） is generated under the reaction between radicals, SF5 and SF5 O. Only a very small amount of SF5 and SF5 O can be generated, and they have little chance to coexist under any kinds of discharge. Thus a relatively small amount of S_2OF_（10） is produced. On the basis of the above analysis and field test results of discharge chamber in GIS, it can be concluded that S_2OF_（10） has little contribution to assessing latent defects in GIS and therefore is not valid to be used as a target gas of partial discharge.