Breakdown characteristics of CF3I and CF3I/N2 gas mixtures in uniform field

摘要

With its high insulation capability and excellent environmental friendliness, CF_3I has been considered as a potential substitute to SF_6. However, considering its high boiling point, CF_3I should be mixed with buffer gases such as CO_2 or N_2. In this paper, breakdown performance of CF_3I/N_2 gas mixtures, SF_6/N_2 gas mixtures and pure SF_6 gas in uniform field are investigated, with negative dc voltage or negative lightning impulse voltage applying. DC breakdown experiments of pure CF_3I gas and pure SF_6 gas show that the dielectric strength of CF_3I is not always higher than that of SF_6. The insulation experimental results show that in low pressures, 30%CF_3I/70%N_2 gas mixtures present similar insulation properties as 20%SF_6/80%N_2 gas mixtures. Considering liquefaction temperature and insulation properties, 30%CF_3I/70%N_2 gas mixtures could be possible substitutes to SF_6 or SF_6/N_2 gas mixtures in low pressures, and it is significant to study their insulation strength in higher pressures.