Based on a large number of engineering practices

free conducting wire-type particles threaten insulation of facilities more severely compared with sphere-type particles

and particles tend to lift off under a DC voltage. Therefore

we specially designed a free conducting particle experimental device and an observation system to study the motion behavior of free wire-type conducting particles in SF

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gas. The results show that lift-off electric field strengths are unchangeable with gas pressure; when lengths of particles increase

lift-off electric fields strengths will increase slightly. When the radius of particles increases

lift-off electric field strengths will increase exponentially; when the length of particles is short

the experimental value and c

alculated value lift-off electric field will be similar as the radius of particles increase; when the length of particles is longer than 3 mm

the experimental value and calculated value are noticeably differential as the radius of particles decreases. Besides

special phenomena of wire-type particles in SF

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are discussed

and it is found when the length increases

and the radius decreases or the gas pressure decreases

the appearance probability of "Firefly and Standing still" phenomenon will increase

and the phenomenon will easily appear on the negative electrode. Lastly

the experimental phenomenon is explained in the view of space charge.