Online detection method and experimental study of SF6 decomposition products based on colorimetric reaction

To address the challenge of online monitoring of decomposition products in SF₆-insulated equipment, a colorimetric detection method based on solid-phase diffusion-reaction coupling was proposed. This method provides high sensitivity and selectivity for early warning of trace fault products inside the equipment. Sulfur dioxide (SO2), a key fault product, was selected as the target substance. The study constructed a quantitative colorimetric system using acidic gases and solid-supported indicators, achieving interference-free monitoring. Experimental results showed excellent chemical selectivity for SO2, effectively eliminating interference from gases like N2 and CO. The response time was 27 hours at 11.7 µL/L and 144 hours at 4.7 µL/L, verifying its dynamic monitoring capability for faults of varying degrees. This technology demonstrated excellent stability in long-term outdoor simulations, offering a passive, maintenance-free, low-cost solution for online state perception and fault early warning in SF₆-insulated equipment.