The defect of foreign matter in gas insulated metal enclosed switchgear is one of the important defect types that affect the safe operation of the substation.The ultrasonic and UHF partial discharge detection methods used in the on-site live detection can realize the detection of foreign particle defect

but can not effectively judge the characteristics of foreign particle in the equipment.In this paper

takes a 126 kV GIS foreign particle as the detection case

analyzes the relationship between pulse pattern and free conducting particle discharge

carries out the theoretical analysis of the force on the foreign particles

establishes the dynamic model of the particles

obtains the simulation results of the movement track of the foreign particles in GIS by using numerical simulation

thus puts forward the flight time-altitude map

and establishes the flight time altitude map library of the typical foreign particles.The results of experiments and field GIS disintegration show that the map library can reflect the flying characteristics of particles

and the experimental flight map library is consistent with the simulation results and case map library

which proves that the flight time altitude atlas can effectively predict the state information of foreign particle defects in GIS.