Propagation properties of PD-induced electromagnetic wave in 66 kV GIS model tank with L branch structure

The authors investigated the effects of a corner that affects the transmission characteristics of a partial discharge (PD) induced electromagnetic (EM) wave, using a gas insulated switchgear (GIS) model with an L-shaped branch. The authors also experimentally investigated the change of amplitude of PD-induced EM wave around the passage of the Lshaped part using a disc-type ultra-high frequency (UHF) sensor located in a 66 kV model GIS. In addition, the effects of transverse electric (TE) mode were examined using a low pass filtering process, and a finite difference time domain (FD-TD) simulation with a simple model was performed. Subsequently, the effects of the L-shaped part that affected the EM wave transmission characteristic were discussed based on a comparison of the results with the analysis. It was found that the effects of the L-shaped part that affected the transmission characteristics of the PD-induced the EM wave did not affect the transverse electromagnetic (TEM) wave mode component, and reflection was generated with a higher frequency component above TE11 mode. It was also shown that the amplitude of the propagating EM wave changed significantly around the L-shaped part due to the superimposition of the reflected TE mode on the latter part of the incoming EM wave.