Power Frequency Breakdown Characteristics of HFO/N-2 Gas Mixtures Under an Extremely Nonuniform Electric Field

Trans-1, 3, 3, 3-tetrafluoroprop-1-ene (HFO) is an environmentally friendly gas that has the potential to replace sulfur hexafluoride (SF6). In this work, the breakdown characteristics of a HFO/N-2 gas mixture were studied under an extremely nonuniform electric field, and the effects of pressure and mixing ratio on breakdown characteristics were analyzed. In the test, a SF6/N-2 gas mixture was used as the control group for comparative analysis. The results show that when the electric field nonuniformity coefficient is high, the breakdown voltage of pure HFO gas shows an "N" type curve with an increasing pressure due to the homogenization of the electric field by the corona. Because of a change in the mixing ratio and electric field nonuniformity coefficient, the breakdown voltage of the HFO/N-2 gas mixture varies linearly or peaks with pressure. The breakdown voltage of the HFO/N-2 gas mixture shows a synergistic effect with the mixing ratio at low pressure and a positive synergistic effect at high pressure. Considering the liquefaction temperature and insulation strength of the gases, HFO/N-2 gas with a 40% volume fraction has the potential to replace SF6.