Analysis of Phase Resolved Partial Discharge patterns with microstrip antenna

Microstrip antennas can be used for measurement of electromagnetically radiated partial discharge (PD) signals in high voltage rotating machines. PD characteristics such as PD magnitude, Phase Resolved Partial Discharge (PRPD) patterns, and frequency spectra have been analyzed using three different antennas and a capacitive coupling device. Some generator stator bars with an artificial defect which might occur in high voltage rotating machines during a long term operation were used as PD sources in the experiments. The microstrip antenna which detects ultra-high frequency (UHF) of 1.8 GHz have shown high sensitivity to some defects, and distinctive PRPD patterns have been obtained depending on types of defects on stator bars. Since one of the most important roles of on-line PD monitoring is to detect insulation deterioration at an early stage, the analysis of PRPD patterns is of great benefit for the condition assessment of high voltage rotating machines in order to be able to operate them stably for a long time.