Measurement of Moisture Content in Gas Insulated Switchgear based on Tilted Fiber Bragg Grating

Detecting moisture content in Gas Insulated Switchgear (GIS) is crucial due to its impact on insulation resistance, posing risks to secure and stable operation. At present, the primary method for detecting moisture content in GIS is the dew point meter, but it lacks in-situ monitoring capability and requires releasing insulating gas during the monitoring process. In this paper, a fiber optic moisture sensor based on Tilted Fiber Bragg Grating (TFBG) is proposed for insitu detection of moisture. The principles underlying the detection of moisture using Graphene Oxide (GO) humidity sensitive film and TFBG were investigated. The GO humidity sensitive film was deposited on the TFBG surface using a modified deposition method, enhancing film thickness and subsequently improving moisture measurement sensitivity. A platform for moisture measurement was established, and experiments were conducted to test the TFBG moisture sensor. The experimental results indicate that the proposed TFBG moisture sensor exhibits a sensitivity of $0.089 \mathrm{pm} / \mathrm{ppm}$ within the moisture detection range of $13-1943 \mathrm{ppm}$, with a detection limit of 22.5 ppm. The TFBG moisture sensor proposed in this paper enables high-sensitivity, in-situ detection of moisture content in insulation gas of GIS.