一种新型碳纳米管气体传感器的响应特性研究

Response Characteristics of a New-style Carbon Nanotubes(CNTs) Gas Sensor

基于碳纳米管(CNTs)气体传感器的SF6气体分解产物检测技术,是诊断GIS绝缘缺陷引起的局部放电的有效手段。开展传感器对SF6分解气体响应特性的研究,对于将该技术应用于GIS局部放电的监测具有重要意义。笔者测量了CNTs气体传感器对4种标准气体(HF、SO2F2、SOF2/S2OF10、SO2)的响应,并建立了由GIS模拟罐体、基于脉冲电流法的局放仪和CNTs气体传感器构成的实验系统,测量了CNTs气体传感器对局部放电形成的SF6分解气体的响应,研究了传感器在多次测量中的重复性以及其响应随局放的变化规律。结果表明,在SO2F2和SOF2/S2OF10气体环境中传感器响应特性明显,且对SO2F2更加灵敏;SO2和HF则基本不引起传感器的电导变化。传感器能够成功检测到针板电极模型引起的局部放电,传感器的电导值随着放电时间的增加而逐渐增加,其响应也随着局部放电能量的增加近似呈线性增加的趋势,最终传感器响应出现饱和趋势。传感器的测量具有重复性,两次测量相差低于0.5%。SF6气体分解产物的气相色谱及红外光谱分析证实了上述结果的合理性。文中使用的标准气体浓度较低,因此关于SO2和HF无法引起传感器响应的结果仍需要利用高浓度标准气体进一步验证。

The technology for detecting decomposition products of SF6 based on carbon nanotubes （CNTs） gas sensor can effectively diagnose the partial discharge （PD） caused by insulation defect in GIS. In this study, the responses of the CNTs gas sensor to four standard gases, i.e. HF, S02F2, SOF2/S2OFlo, and S02, were measured, and an experimental system was set up, which consists of a GIS simulation device, a PD detection instrument based on pulse current method, and a CNTs gas sensor. Then, the decomposition gas of SF6 resulting from PD was measured by the CNTs gas sensor, the variation of conductance of the gas sensor with PD was obtained, and the repeatability of the gas sensor＇s response was analyzed. The results show that the gas sensor displays significant SOF2/S2OFlo gases, and it is more sensitive to SO2F2. However, SO2 response characteristics in SO2F2 and and HF induce little change in the conductance of the sensor. The sensor exhibits clear response to the PD generated by point-plane electrode model. Furthermore, the conductance of the gas sensor increases gradually within the duration of PD, and its response increases almost linearly with the accumulation of partial discharge energy until gets saturation. The gas sensor shows good repeatability with the difference between two measurements less than 0.5%. The analyses of gas chromatography and infrared spectroscopy on decomposition products of SF6 verify the correctness of the proposed gas sensor.