Partial discharge measurement in a long distance SF6 gas insulated transmission line (GIL)

We evaluated the generation, radiation, and propagation characteristics of partial discharge (PD) signals in 275 kV full-scale SF₆ gas insulated transmission line (GIL) model with a length of 168 m. We analyzed the correlation between the PD current pulse and the radiating electromagnetic wave by comparing their frequency spectrums. In addition, simultaneous measurement was performed on the current pulse waveform of a single PD and the corresponding electromagnetic wave as propagated in GIL, with the phase gate control method. As a result, the PD signal attenuation rate of 50 MHz and 300 MHz for the propagation of 100 m was obtained as 2.5 dB and 8.7 dB, respectively. Furthermore, by selecting an appropriate measuring frequency, even a 1~2 pC PD could be detected at the measuring site 168 m away from the PD source in the GIL