A nonintrusive partial discharge measurement system based on RF technology

Conventional electrical measurements of PD are performed with detectors connected to the plant. This paper describes research conducted in conjunction with the National Grid Company and the radiocommunications agency for the radiometric detection of partial discharge sources via a novel noncontact digital method. The equipment uses an antenna sensor and reference voltage inputs which are directly sampled at 2.5 GHz. Results for hv laboratory tests involving air, SF6 and oil discharges are presented. The results include the waveform, average frequency spectrum and pulse count distribution. A proposal is made for the characterisation of the recorded impulses from these different breakdown effects based on analysis of the spectra and pulse count distributions.