Influence of SF₆/N₂ Mixed Gas Pressure on the Arc Control Ability of the Main Electrode in the Trigger Gap

Abstract

In the controllable self-recovery energy-absorbing apparatus of the Baihetan-Jiangsu Hybrid UHVDC Transmission Project, a 30%SF6/70%N2 mixed gas is employed as the insulating medium within the trigger gap switch. In order to mitigate surface erosion on the main electrode of the trigger gap switch, as well as the inner wall of the insulating sleeve, and to reduce the usage of SF6, an investigation into the arc control ability of the main electrode under different pressures of the mixed gas has been initiated. The motion characteristics of the arc within the gap have been simulated using a Magnetohydrodynamics (MHD) model, and the variation pattern of the main electrode’s arc control ability within the pressure range of 0.1MPa to 0.4MPa was obtained by analyzing the changes in the arc volume. The arc control ability of the main electrode is influenced by the differences in physical parameters of mixed gas at different pressures. Results indicate that the electrode’s arc control ability experiences an initial increase followed by a subsequent decrease with the rising pressure of 30%SF6/70%N2 mixed gas. Notably, within the pressure range of 0.1MPa to 0.4MPa, the main electrode exhibits the highest arc control ability when the pressure of the mixed gas is 0.3MPa.