Sensing of Decomposition Products in SF₆ by Use of a Corner Cube Prism Coated with a Dye Film as an Optical Sensor Head

A very sensitive optical sensing method for detecting a small quantity of gaseous decomposition products generated by an electric discharge in SF 6 was developed. A sensor head is prepared using a corner cube prism of which three total reflection planes are coated with a thin film of methyl orange dye deposited by a vacuum evaporation method. The methyl orange dye is a color reaction reagent for detection of SF 6 gas decomposition products such as HF gas, which is generated due to discharge induced in a glass container filled with SF 6 gas. The sensor head connected to a halogen lamp through an optical fiber is placed in the container. This optical sensing method can be used to detect in real time problems or failure occurring in gas-insulated equipment.