抄録
Electromagnetic waves have come to be used for measuring partial discharge, which is indispensable for predictive maintenance for GIS. The UHF method, using the frequency band of 300MHz to 3GHz with generally less noise is one of the advanced technologies of insulation diagnosis of GIS. There are three categories of electromagnetic wave propagating in coaxial cylindrical structure like GIS, namely, TEM, TE, and TM modes. In the frequency region above the cut-off frequencies of the TE or TM mode, the resonance characteristics of each mode that depend on the length of the waveguide and the cut-off frequency are appeared. When the coaxial waveguide has one or two spacers inside itself, the output characteristics of UHF sensor at the resonant frequencies are different by the number, the layout and the thickness of spacers. This paper describes the effect of spacers on the output characteristics of UHF sensor in non-reflection coaxial waveguide at the resonant frequencies of TE11 mode.
