Characterization of acoustic signal and pattern recognition of free moving metallic particle motion modes in GIS

Free metallic particles inside the Gas Insulated switchgear (GIS) apparatus are considered hazardous to the insulation system which can be detected using acoustic sensors placed on the enclosure. From acoustic measurements, it is rather easy to determine the partial discharge pulses caused by loose or fixed particles. One can readily recognize the motion modes of the free particle by studying the acoustic signal. This paper presents the analysis of free metallic particle motion modes in GIS apparatus from acoustic measurements. The parameters such as maximum acoustic amplitude, number of acoustic pulses, mean value of maximum amplitude of 10 measurements, number of pulses which exceed the specified % of maximum amplitude characterizing partial discharge activity of Al as well as Cu particles of different shapes are investigated.