Risk assessment basis of Acoustic Signal from Free Moving Metallic Particles in GIS

To study the risk of free moving metallic particles in gas insulated switchgear (GIS) chamber, a test cell is designed to simulate this defect. A lot of acoustic signals emitted by different shape and different size particles are measured to extract parameters of acoustic signals such as the phase correlation, amplitude and flight time. Then the criticality of particles is analyzed basis on these parameters. By analyzing the experimental results, the acoustic signals are weak and show a strong phase correlation when the discharge is caused by the static particles on the enclosure, however, the acoustic signals are strong and show a weak phase correlation when the particles are dancing on the enclosure. It also shows that the flight time varies with the particles' shape and size, and the cylindrical particles' flight time is more sensitive to the test voltage than that of the spherical. This means that they have different criticalities to the insulation of GIS. Moreover, the signal amplitude and particles flight time also have periodicity. Finally, a case is studied which verifying the finding of the paper.