Hydrogen Gas Sensing in Transformer Oil by Surface Acoustic Wave Sensors

Both the thermal faults and electrical faults may lead to hydrogen gas generation that dissolved in transformer oil. Diagnosis and early warning of transformer faults have been widely recognized by detecting the content change of dissolved hydrogen gas in the oil. This work aims to detect the change of hydrogen-gas content in transformer oil by using the surface acoustic wave (SAW) sensors. The sensing is recognized through the wavelength variation of SAW. The mass change of the sensitive layer due to the absorption of hydrogen-gas molecular is found to lead to significant changing of the SAW wavelength. By the controlled sputtering parameters, this work takes layer-structure optimized SnO2and Pd to build up the sensing layer. The hydrogen selectivity of Pd film, the sensitivity of the sensor is enhanced effectively by increasing the surface process of the bilayer sensitive film. The results indicate that the sensitivity of the processed sensor is 1.4 times as high as that before the processing.