Resonance characteristics and identification of modes wave excited by partial discharges in GIS

The mode of electromagnetic wave generated by a partial discharge (PD) in a GIS (gas insulated substation) is discussed. Peaks in the frequency spectrum excited by PD are identified in its mode and the resonance characteristics of each mode are studied. It is shown that the excitation of each mode strongly depends on the radial position of PD source. This dependence is explained based on the general theory of electromagnetic waves in a co-axial cylindrical cavity.