光电子电离质谱在线监测SF_6气体分解物

Online Monitoring the Discharging Products of SF_6 with Photoelectron Ionization Mass Spectrometry

电气设备内部放电故障的原因与其中SF6杂质气体的种类和含量相关。本工作设计了一套基于光电子电离飞行时间质谱的在线监测系统,通过对电气设备腔体内SF6气体组分的实时监测,实现电气设备放电故障的诊断。同时,结合实验室研制的SF6气体低压放电系统,研究了不同掺杂气的SF6气体放电产物谱图和动力学监测曲线,初步探讨了不同条件下SF6放电产物的产生机理。该技术有望实现在线质谱分析技术进入电力生产现场和及时监控SF6电气设备内部故障情况。

Sulfur hexafluoride （SF6） is a gas used in electrical substations at electric power plants as an insulator in circuit breakers and switchgear. SF~ gas can generate a variety of decomposed products due to discharge or overheat inside the high-voltage devices. The discharging fault inside of the electric device insulated by SF6 is closely re- lated to the composition and content of SF6 gas discharge products. Some of the byprod- ucts are active and unstable, which create difficulties on testing them and have to be ana lyzed through a variety of testing methods. Gas chromatography, gas chromatography- mass spectrometry and infrared spectrometry have been developed to rapidly analyze the discharge products, but these methods are time-consuming and very hard to realize the in situ analysis and on-line diagnostics. An online monitoring system for discharging products of SF6 with photoelectron ionization （PEI） time-of-flight mass spectrometry was developed in this paper. It can be used for diagnosis of discharging fault inside of the electric device by real-time monitoring for discharging products of SF6. The mass spectrum of SF6 gas discharge products and the kinetics were investigated using a gas discharging study with home-made low direct current voltage system. The main byprod- ucts of SO2F2, SOF2, SO2 and SF4 can be clearly detected. This method is expected to provide the power production field with online mass spectrometry monitoring and track the fault inside of the SF6 electrical equipment on its running condition.