4th International Conference on Electric Power Equipment– Switching Technology (ICEPE-2017)

384 / 2017-04-24 15:11:27

Research on the Discharge Behaviors of SCF N2

SF6 has been widely used in the electrical equipment，but as a greenhouse gas, the long-term effects of SF6 on the global warming is not ignored. Reducing and controlling greenhouse gas emissions is a pressing issue. Therefore, it is urgently find an economical and feasible scheme to replace SF6. The supercritical fluid N2 exhibits good dielectric properties, recovery performance and environmental friendliness (GWP is equal to 0). Therefore, the research about discharge characteristics of SCF N2 has attracted the overly attention of the worldwide scientists.
This paper established the rod-plate electrode model with 5mm gap, DC voltage is applied, using the fluid dynamics equations are studied in supercritical fluid nitrogen under the pressure of 1-5MPa and temperature 126-300K, acquired the relationship of breakdown field and atmospheric pressure, and compared the breakdown process of supercritical nitrogen in 3.4MPa and nitrogen in normal atmospheric pressure. Meanwhile, charged particle dynamics are analyzed, hence the evolution of the space charge, the distribution of electric field intensity, and discharge obit of the SCF N2 breakdown process are discovered. Furthermore, the recovery characteristics of supercritical nitrogen were studied. The results show that the breakdown voltage increases with the increase of pressure until the 5Mpa pressure, and the apparent saturation trend is not observed. Under the supercritical condition, the N2 breakdown strength reaches 77.7% that of the SF6. After the supercritical nitrogen discharge, the temperature is reduced to 5000K in 6.3*10-6s , and it is considered that the dielectric has been recovered.
The SCF N2 is proved to be a promising dielectric medium for replacement SF6.