Movement of free conductive particles is one of the main causes of failure of gas insulated transmission line（GIL）. So it is of great significance for ensuring the safe and reliable operation of GIL equipment to study the movement and suppression of free-conducting microparticles in GIL. We analyzed the distribution of electric field near pot-insulators in GIL and the law of trapping and movement of spherical free conductive particles. The results show that the electric field near the pot-insulator and the outer shell in the GIL is similar to the wedge-shaped electric field distribution. And also

there are some differences. Therefore

apart from the similarity

the particle motion in GIL will have some differences from the wedge electrode. That is

the larger particles will climb along the surface of the pot-insulator and attach to the surface or collide with the guide rod eventually. Constructing a trap on the GIL shell will distort the electric field around

causing the free particle to take off position prior to the absence of a trap. Meanwhile

the width and depth of the trap will affect the nearby electric field. Compared with the depth change

the electric field near the trap increases more significantly when the trap width increases. Based on the analysis

the construction rule of the trap is discussed

and the concept of the critical trap and capture value is proposed to divide the effective trap range.