Most optical hydrogen sensors are based on light intensity measurement and light intensity detection is vulnerable to the light source output and the optical fiber arrangement. To overcome the shortcomings, an optical fiber based sensor based on fiber Bragg grating (FBG) technique which is capable to measure the concentration of hydrogen dissolved is described in this paper. To examine the availability of monitoring initial hydrogen generation, a needle-to-plate partial discharge (PD) model was setup in the lab. The results between wavelength shifts of optical hydrogen sensor well agreed with conventional dissolved gas analysis (DGA), proving a potential utilization in the detection of dissolved hydrogen in power transformer.

A novel gas flow sensing probe based on silver-coated Fiber Bragg Grating (FBG) is proposed. A square hole was fabricated in the middle of a capillary stainless steel pipe. A silver-coated FBG sensing probe was fixed up between the hole. The diameter of the silver-coated FBG sensing probe is only 0.125 mm, with the PVC materials deposited around the surface of the both ends with a diameter of 0.9 mm. Simulations on different packages of sensing probe were carried out via Finite Element Method (FSM). Results of the simulations reveal that the sensing probe of the capillary stainless steel pipe with a diameter of 3 mm and the square hole with a length of 12 mm can provide the best performance.