Highly Sensitive Dissolved Hydrogen Sensor Based on Side-Polished Fiber Bragg Grating

• Published in: IEEE photonics technology letters Vol. 27; no. 13; pp. 1453 - 1456
• Main Authors: Jiang, Jun, Ma, Guo-Ming, Li, Cheng-Rong, Song, Hong-Tu, Luo, Ying-Ting, Wang, Hong-Bin
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.07.2015; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Bragg gratings; Cladding; dissolved hydrogen; fiber Bragg grating; Fiber gratings; Fibers; Hydrogen; Natural gas; Oil insulation; Optical fiber sensors; Palladium; power transformer oil; Power transformers; residual thickness; Sensors; side polished; Temperature sensors; Transformers; fiber Bragg grating; residual thickness; dissolved hydrogen; Side polished; power transformer oil
• ISSN: 1041-1135; 1941-0174
• DOI: 10.1109/LPT.2015.2425894

To eliminate the time-consuming oil-gas separation process in online dissolved gas detection of power transformer, fiber Bragg grating (FBG)-based hydrogen sensor is proposed to be installed into the power transformer oil directly. In the sensor design, the FBG cladding is side-polished with a residual thickness of 20 μm and sputtered with palladium/silver. Since side-polished cladding is very sensitive to curvature strain induced by palladium in the presence of dissolved hydrogen, the proposed sensor is much more sensitive than the untreated FBG hydrogen sensor. Measurements prove that the sensitivity is as high as 0.477 (pm/(μL/L)), about 11.4 times higher than the conventional FBG hydrogen sensor. Furthermore, repeatability and short-term stability have been investigated. The performances satisfy the actual need of monitoring dissolved hydrogen concentration in power transformer oil.