Dissolved hydrogen measurement with palladium-silver FBG sensor in transformer oil

A novel sensor used in detection of hydrogen concentration dissolved in transformer oil was proposed based on fiber Bragg grating (FBG). Palladium was introduced as hydrogen sensitive material and silver was alloyed to improve permeability in hydrogen sensitive layer. Meanwhile membrane of titanium was fabricated for enhancing the adhesion between fiber and hydrogen sensitive layer. The thin film on FBG was coated with magnetron sputtering. A novel sensor that was wavelength-sensitive to hydrogen dissolved in oil was fabricated and the experimental platform was set up in this paper. The sensitivity of the sensor was tested in transformer oil at 80 °C which was typically high operating temperature or local overheating temperature of power transformers. The experimental result demonstrated that the sensor performed well at low hydrogen concentration of 323 µL/L and the sensitivity of sensor was as high as 24.4 µL/L at every 1pm wavelength shift.