Simulation Study of Low Temperature Liquid Nitrogen Switching Discharge Characteristics under Multi-Electrode Conditions

Sulfur hexafluoride (SF 6 ), as an arc extinguishing and insulating medium for circuit breakers, is prone to decompose at high temperatures, generating toxic gases and contributing to the greenhouse effect. Liquid nitrogen (LN 2 ) is considered to be an effective alternative to SF 6 due to its good insulating properties. In this paper, the discharge characteristics of a metal-enclosed liquid nitrogen switch based on different conditions are investigated. The local thermal equilibrium (LTE) model is used as the reference. In addition, changes in velocity and temperature results inside the chamber were observed depending on the electrode geometry, material, and initial LN 2 temperature. The results show that changing only the initial LN 2 temperature does not affect the temperature inside the chamber and that the initial LN 2 at 68.15k makes the velocity change smoother. Compared to the other types, the plate-plate-shaped stainless-steel electrodes showed smoother temperature and velocity changes after discharge.