The shape

size and material of the metal particle significantly affect the original insulation strength.The motion of particles is an important reason of the breakdown of GIS. The detection of metallic particles in GIS mainly relies on the partial discharge measurement. The movement behavior and the partial discharge of particles with different sizes are different under the operation voltage. Therefore

the relationship between the partial discharge and movement behavior of metal particles should be established

and the size of linear particles may be estimated by the partial discharge. In this paper

the movement behaviors of metal particles with different sizes in the GIS are simulated. A 126 k V GIS prototype proportion shrinking test chamber is set up in the laboratory. Different sizes of linear particles are placed respectively in GIS and their discharge signals are detected by the conventional pulse current detector and ultrasonic detector. The particle motion trajectory is taken by a high speed camera. The results indicate that

the movement behavior of metal particles with different length and radius are different

and the jumping height and flight time increases with the decrease of particle diameter or the increase of particle length. The collision frequency depends on the size of metal particle. The particle collision is sensitively detected by ultrasonic detector and the collision frequency could be estimated by the frequency of ultrasonic signals. There is a certain proportion relation between the maximum measurement apparent discharge amplitude and the maximum charge of particle

and the proportion relation is basically consistent when the size of particle is not charged. The size of metal particle can be estimated by comparing the maximum apparent discharge amplitude and the ultrasonic pulse frequency.