In order to study the decomposition characteristics of SF

6

under floating potential defects

an experimental platform with a physical model of floating potential defect was constructed.Partial discharge and decomposition experiments were then performed under different applied voltages and pressures.Experimental results show that main decomposition products under floating potential defects include SO

2

F

2

SOF

2

CO

2

and SO

2

among which the formation rate from high to low in order is:CO

2

SOF

2

SO

2

F

2

and SO

2

.The volume fraction vari

ation of the main products（φ） is affected by the applied voltages and pressures.Besides

the values of φ（SOF

2

+SO

2

）/φ（SO

2

F

2

） and φ（SOF

2

+SO

2

+SO

2

F

2

）/φ（CO

2

） maintain stable with the prolonging of pressurization time.Therefore

it is possible to judge the strength of PD and the type of insulation defects by utilizing the volume fraction variation of typical decomposition products and their concentration ratios.