Abstract：Ultra-high frequency (UHF) electromagnetic waves (EM-waves) excited by partial discharge (PD) in gas insulated switchgear (GIS) can hardly be applied effectively to evaluate the PD source signal level as the EM-waves are affected by the GIS structure. For studying the influence of GIS structure on the EM-wave signals, the attenuation characteristics of EM-waves in different parts of GIS are investigated by using FDTD method in this paper and the spacer attenuation characteristic in actual GIS is studied with UHF sensors. The simulation results show that EM-wave signal amplitude will decrease a lot as the disperse effect of high order modes in coaxial waveguide, but the energy propagation is hardly affected. The EM-wave attenuation of the insulator which is near PD source is more serious than other insulators. EM-wave amplitude and energy both attenuate a lot when it pass L branch, but TEM mode attenuates a little. The attenuation of EM-wave in plumb way is more serious than straight way when signals propagate through the T branch.
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2010, Vol. 25 
