An investigation into the effect of insulation defect on radiometric partial discharge measurements

Measuring partial discharge (PD) activity in high voltage plant using radio frequency (RF) equipment is a well-established technique used to monitor insulation integrity. This paper presents a study of partial discharge behaviour involving gaseous, liquid and solid dielectrics typical of insulation defects that may occur in practice. Discharge pulses with varying rise times and decay times were simulated using a double exponential pulse shape to represent PDs in different dielectrics. The results show how the differing rate of change of current among PD pulses affects the frequency spectra and energy spread of the radiated RF signals. In the RF PD experimental measurements, results are in accordance with the simulation results which incorporated the effects of changing PD behaviours in different dielectrics. It concluded that PDs in different insulating systems produce varying physical effects corresponding to the different discharge mechanisms. These results can provide insight for the interpretation of signals from radiometric PD measurement systems.