Application of the Short Time Fourier Transform in Evaluation of the Acoustic Emission Signals Generated by Partial Discharges

The subject matter presented in this paper deals with application of the short time Fourier transform (STFT) in processing the acoustic emission (AE) pulses generated by six basic forms of partial discharges (PDs) that can occur in insulation systems of power appliances. The paper presents the time-frequency analysis results of the AE pulses generated by the following spark gaps modeling the following PD forms: point-plane type discharges in oil, multipoint-plane type discharges in oil, multipoint-plane with a layer of pressboard, surface discharges in oil, gas bubble discharges in oil, discharges in indeterminate-potential particles moving in oil. For each of the PD forms the STFT was determined and the corresponding spectrogram and three-dimensional spectrogram of amplitude or power spectrum were drawn.