In order to further apply SF

6

/N

2

in power equipment

we studied the breakdown characteristics of SF

6

/N

2

in different electric field non-uniformity via fully enclosed power frequency experimental apparatus

and studied the characteristics of partial discharge inception voltage in non-uniform electric field.The research indicates that the breakdown voltage of SF

6

/N

2

gas mixtures increases linearly with increase of gas pressure in slightly non-uniform electric field.With increase

of the electric field non-uniformity

the saturated trend of breakdown voltage appears.When electric field non-uniformity exceeds a certain value

the stable corona discharge appears before the electric breakdown of electrodes gap.The N-curve characteristic of breakdown voltage appears in SF

6

and its mixtures.With the increase of electric field non-uniformity

the amplitude and range of N-curve extend.With the increase of electric field non-uniformity

the synergistic effect becomes more significant and then is weakened.The significant phenomenon of critical radius can be found in pure N

2

and the critical radius is around 1 mm to 2 mm.However

the phenomenon is not obvious in gas mixture and pure SF

6

and with the decrease of the electrode radius of curvature

the breakdown voltage decreases obviously under high pressure

while it increases under low pressures.