Identification of a specific type of PD from acoustic emission frequency spectra

The paper presents an attempt to apply spectral analysis tools in processing acoustic emission (AE) pulses generated by partial discharge (FD). The experimental part of the paper describes spark gaps generating four types of PD and specifies parameters of measured acoustic signals and recalls the system used for measurement and analysis of the frequency spectra. Also, a spectral analysis procedure is presented, and frequency-domain descriptors characterizing AE pulses are defined. The results of the analysis are given both as time plots and amplitude and energy density spectra, related to values of the associated descriptors. The spectral analysis results cover AE pulses generated in systems modeling the following types of pD: point-plane type discharges in oil, surface discharges in oil, gas bubble discharges in oil and discharges in indeterminate-potential particles moving in oil. In conclusion, an ability to identify a specific type of FD on a basis of frequency spectra of AE pulses and their descriptors is presented. The comparative analysis enables one to select those descriptors, which can constitute unique criteria for identification of a specific PD type.