Sensitivity Characteristic Analysis of Adsorbent-Mixed Carbon Nanotube Sensors for the Detection of SF6 Decomposition Products under PD Conditions

Sulfur hexafluoride (SF₆) gas decomposition results from the energy produced by partial discharge (PD). The detection of SO₂ and H₂S content, as important characteristic components of the decomposition products, is significant in the determination of the insulation level of SF₆ gas and the inside insulation faults of gas-insulated equipment. A number of gas sensors use carbon nanotubes (CNTs). However, the applications of these sensors are limited by their low intrinsic sensitivity. In this paper, an adsorbent-mixed carbon nanotube gas sensor is proposed to improve the detection of SO₂ and H2S concentrations. The sensitivity of adsorbent-mixed carbon nanotube gas sensors to SO₂ and H₂S at 100 ppm was investigated experimentally. The effect of the mixing ratio on the gas sensitivity characteristic and mechanism of response was also studied. The results show that compared with intrinsic CNTs gas sensors, the gas sensor featuring adsorbent-mixed CNTs has significantly higher sensitivity and responsiveness to SO₂ and H₂S. The resistance-change rate of SO₂ and H₂S increased to 33.7% and 50.9% from 0.96% and 12.9%, respectively. Moreover, the resistance-change rate and gas concentration satisfy a linear relationship. The sensor has good repeatability and stability.