Detection of wide-band E-M signals emitted from partial discharge occurring in GIS using wavelet transform

Recently, diagnostic techniques have been investigated to detect a partial discharge (PD) associated with a dielectric material defect in a high-voltage electrical apparatus. Gas insulated switchgear (GIS) is an important equipment in a substation, it is highly desirable to measure a partial discharge (PD) occurring in GIS which is a symptom of an insulation breakdown. As it is important to develop a noncontact method for detecting the insulation fault, this paper proposes a new method to detect the wide-band electromagnetic (E-M) wave emitted from PD using the Wavelet transform. The Wavelet transform provides a direct quantitative measure of spectral content, “dynamic spectrum”, in the time-frequency domain. This paper experimentally shows the “dynamic spectrum” of the wide-band E-M wave emitted from PD in the time-frequency domain. This method is shown to be useful for detecting the symptom of the insulation breakdown occurring in GIS