The influence of T-shaped structure on partial discharge radiated electromagnetic wave propagation in GIS

When ultra-high-frequency (UHF) method is applied in partial discharge (PD) detection for GIS, the propagation and rules of electromagnetic (EM) wave need to be understood clearly for conducting diagnosis and assessment about the real insulation status. The preceding researches are mainly concerning about the radial component of electromagnetic (EM) wave, but the propagation of the components in axial and radial directions and that perpendicular to the radial direction of the GIS tank are rarely considered. So in this research, in order to clarify the propagation process and improve the utilization of UHF technique in PD diagnosis, the propagation characteristics of EM wave in different directions in a 252 kV GIS with T-shaped structure (TS) are profoundly investigated. The attenuation rules of the peak to peak value (Vpp) and cumulative energy are concluded. According to the property of electric field distribution and attenuation curves of the UHF signal, the influence of T-shaped structure is analyzed. This paper discusses the propagation mechanism of UHF signal in T-shaped tank, which provides a better understanding of the PD propagation process as well as some referential significance towards the utilization of UHF technique.