An On-Line Monitoring System of SF₆ Decomposition in Electrical Devices

Abstract:

This work is dedicated to the development of an on-line monitoring system of SF6 decomposition in electrical devices (SF₆DcpMS) in order to evaluate the health condition of the devices in real time. The feature decomposition, SO₂, and SF₆ purity are continuously monitored. Considering the oxidation-reduction reactions of SO₂ electrochemical sensor during detection, the methodology of utilizing the air in the electrical device is proposed based on the tests of serving devices. And it is proved via tests that electrochemical sensors can be applied into SF₆DcpMS. Besides, infrared detector is employed to detect SF₆ purity. Sampling method of SF₆ in electrical devices is described. There are three keys in the sampling device design for the on-line monitoring system: -- Sensor working environment: The rating pressure is one atmospheric pressure for sensor working. Therefore, a gas chamber is constructed, in which the suitable environment for sensor is completed via a pressure regulator and a pressure sensor. At the same time, an appropriate control method is scheduled. Gas in the chamber is continuously replaced with that in the electrical device to ensure detection accuracy within an acceptable range. -- SO₂ adsorption feature: The monitoring accuracy is seriously influenced by the adsorption feature of SO₂. As we known, flowing gas can decrease SO₂ adsorption feature. So, a micro bump is designed in the gas chamber, which can ensure the gas flowing at the speed of 200ml/min. -- Sample gas back into electrical devices: In order to avoid the gas cause harm to humans, the gas leakage is not allowed in the on-line monitoring system, and the sample gas must be sent back to the electrical device after detection is accomplished. Sample gas back into electrical devices is realized via a bump and a check valve with adjustable cracking pressure. The first SF₆DcpMS in China has been successfully put into service in Zunyi substation, and its performance has been proved out.

• Periodical: Advanced Materials Research (Volumes 718-720)
• Pages: 399-404
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.718-720.399
• Online since: July 2013
• Authors: Hui Xuan Shi, Jin Qian, Xiao Bo Liu, Xiao Li Liu
• Keywords: Decomposition, Electrochemical Detection, Online Monitoring, SF₆ Electrical Device, SF₆ Purity, SO₂

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