Characteristic of Acoustic Emission Excited by Partial Discharge of Multi-Source Defects in SF6 Based on Optical Microphone

The acoustic signal generated during the operation of gas insulated switchgear and gas insulated line (GIS/GIL) contains a wealth of equipment status information. In this paper, the characteristics of acoustic emission signals of three types of electromechanical defects: fixed tip, floating potential and free metal particle have been studied. The results show that, compared with the mechanical defect, the acoustic signal excited by the discharge has a shorter time domain duration and a steeper rising edge; the frequency distribution range is more concentrated and the peak value is obvious. A defect classification method based on the relationship between the equivalent time and equivalent frequency of the acoustic signal is proposed, and the classification and identification of three types of defects are realized. The research has mastered the broadband characteristics of GIS/GIL multi-source defect acoustic emission signals, which has laid a foundation for GIS/GIL diagnosis based on acoustic method.