Analysis of Arc Characteristics of C4F7N/CO2 Mixed Gas Ring Main Unit

Based on the common structure of the arc extinguishing chamber of 12 kV arc extinguishing grid ring main unit, the characteristics of an arc under C
₄
F
₇
N/CO
₂
mixed gas and SF
₆
gas are studied and analyzed. The results show that the SF
₆
gas arc is smaller in diameter than the mixed gas arc, and the value of arcing voltage just before current zero crossing is higher and the breaking performance is better. Based on the magnetohydrodynamic (MHD) model, a three-dimensional computational model of the C
₄
F
₇
N/CO
₂
mixed gas ring main unit is established, and the pattern of the arc motion and its voltage characteristics during the opening process are simulated and analyzed using commercial software. The article simulates and analyses the effect of the structure of the static contact, the structure of the grids, and the material of the grids on the arc movement and characteristics on the arc voltage boost. Static contacts using the “U-shaped” structure is conducive to close to the static contact side of the arc root to move, not in a stable burning point, can reduce the static contact by the degree of arc ablation, and conducive to the arc more into the grids to improve the arc voltage. The structure of deep slotted grids will further increase the arc voltage and the voltage drop can be reduced. The structure of fully insulated grids relies on the principle of elongating the arc length to increase the arc voltage and the arc voltage can be steadily increased. The simulation analysis and research provide a certain guiding significance for the improved design of arc extinguishing chamber of C
₄
F
₇
N/CO
₂
mixed gas ring main unit.