Analysis of Infrared Absorption Characteristics of Insulating Gas SF₆ in High Voltage Electrical Equipments

Infrared detection technology is used for the qualitative and quantitative analysis of SF₆ and its decomposition products—such as SO₂, H₂S, and HF—making it necessary to first analyze their infrared absorption characteristics and cross-absorption. In this study, the infrared absorption characteristics of SF₆ were examined using the HITRAN2020 database, and the infrared cross-absorption among SF₆ and its decomposition products (SO₂, H₂S, HF) was also analyzed. The results show that the infrared absorption band of SF₆ is mainly located in the mid-infrared region at 590–640 cm^-1, 940–952 cm^-1, and in the far-infrared region at 330–370 cm^-1. The peak absorption intensity in the mid-infrared region is more than 10⁴ times greater than that in the far-infrared region. The infrared absorption spectra of these three bands are similar in structure, each composed of a P-branch, Q-branch, and R-branch. The absorption intensity of the Q-branch peak is much stronger than that of the P-branch and R-branch. The infrared cross-absorption bands of SF₆, SO₂, H₂S, and HF are located at 590–600 cm^-1, 330–370 cm^-1, and 350–370 cm^-1, respectively. In terms of absorption intensity, SF₆ and SO₂ are of the same order of magnitude, which is two orders of magnitude lower than that of H₂S and four orders of magnitude lower than that of HF.