Liquefaction of SF

6

can lead to insulation or interruption failures in switchgears that are installed in high-latitude low-temperature regions. Consequently

mixtures are widely used in gas circuit breakers in these regions.The status of the switchgear equipment affects the safe operation of power grids directly

the location of faults and diagnosis of defects are mainly detected by gas decomposition products at present. Consequently

we performed a series of mixture gas decomposition tests on a SF

6

/N

2

gas-insulated ci

rcuit breaker after breaking current

studied the characteristic components of the decomposition products

and analyzed the effects of different arc energy and N

2

content on the decomposition products of the mixed gas. It is found that the decomposition products of SF

6

/N

2

mixture in the presence of electric arc detected by gas chromatograph are mainly CF

4

CO

2

SO

2

and SOF

2

. The concentration of these decomposed products increases with arc energy and time increases. With the same arc energy

the higher the proportion of SF

6

in the mixed gas is

the higher the decomposition products content will be. And the influence of SF

6

ratio on（SO

2

+SOF

2

）/（CO

2

+CF

4

） is also obtained.The studies can provide a reference for the diagnosis of internal defects of SF

6

mixed gas.