The ions mean free path and the thermal motion speeds are different at different temperatures around SF

6

/N

2

mixed gas

thus SF

6

/N

2

mixed gas discharge exhibits a different characteristics.Therefore

under the severe non-uniform electric field and lightning impulse voltage

we studied the breakdown characteristics of SF

6

/N

2

mixed gas along with the temperature change.Moreover

under the positive and negative polarity of lightning impulse voltage

we measured the impulse breakdown voltage and pre-discharge current waveforms

and analyzed the pre-discharge phenomenon

stepping time

corona onset el

ectric field

and breakdown strength in SF

6

/N

2

mixed gas at different temperatures.The temperature range during experiment was set from-20 ℃ to 20 ℃.Results show that the stepping time

corona onset electric field strength

and breakdown field strength present great randomness.The stepping time under negative polarity impulse voltage is longer than that under positive polarity impulse voltage.Under the negative polarity impulse voltage

as the temperature increases

the corona onset electric field and the breakdown strength of 10%SF

6

-90%N

2

mixed gas will increase.The results are of certain research significance in the design of cubicle gas insulated switchgear and gas insulated metal-enclosed transmission line.