In this paper

the power frequency insulation characteristics of nitrogen oxygen mixture under different electric field uniformity

ratio and air pressure are studied by power frequency breakdown test. It is found that the ratio of plate-to-plate electrode has little effect on the power frequency breakdown voltage of nitrogen-oxygen mixture

and the power frequency breakdown voltage of nitrogen-oxygen mixture increases with the rising charging pressure. The power frequency breakdown voltage of nitrogen-oxygen mixture is obviously reduced under rod-plate electrode. The breakdown voltage of nitro-oxygen mixture reaching 0.6-0.9 MPa shows a ‘hump’ effect under the pin-plate electrode. The ‘hump’ effect becomes more and more significant

and the power frequency insulation strength reaches saturation point at higher pressure with the increase of the pin-plate eletrode spacing. Comprehensive analys

is shows that the insulation strength of 80%N

2

/20%O

2

mixed gas with air pressure of 0.8 MPa is equivalent to that of SF

6

at 0.4 MPa under different electric field uniformity. The research results provide reference for the equipment design of nitrogen and oxygen mixture as insulation medium. These results also have important significance for promoting the low-carbon and green development of electrical equipment.