Simulation of Propagation Characteristics of PD UHF Signals inside and outside of Switchgear

Partial discharge (PD) detection has proved to be a convenient, reliable and cost-effective technology in determining insulation deterioration within distribution switchgears. The signals will be different of ultra-high frequency (UHF) sensors used for PD detection of switchgear for different installation locations. In this paper, the differences of detection signals are studied for UHF sensor installed inside and outside of the switchgear. The simulation is carried out based on the finite element method and signals of UHF sensor installed on the inside and outside surface of the switchgear are obtained. The results show that the amplitude and arrival time of the UHF sensors are different for different installation locations. If the PD source and the point probes are in the same cabinet, the point probes of internal installation can obtain significantly enhanced signal strength than the point probes of external installation. On the contrary, the signal strength obtained by point probes of internal installation is almost the same with that obtained by the point probes of external installation.