TEM- and TE-mode waves excited by partial discharges in GIS

The possibility of using information from the TEM- and TE-modes for the detection and location of partial discharges has been investigated. The propagation and attenuation of the E and H components of the different modes excited radially by a line current in a coaxial cylinder is described. To give the verification of it, experiments have been performed with simulated partial discharge currents injected radially in a GIS test facility. It is shown that: both the TEM-mode and TE/sub 11/-mode are excited by partial discharges in GIS; an inductive sensor allows the TEM-mode to be distinguished from the TE-mode; and the discharge location can be determined by employing different propagation velocities of the TEM- and TE/sub 11/-modes.