Analysis of partial discharge sources in stator insulation system using variable excitation frequency.

Identification of partial discharge (PD) sources in stator insulation is an important and challenging task. Distinct phase‐resolved PD (PRPD) pattern of different PD sources are well established at power frequency (50/60 Hz) and can help to identify each source. In this study, different sources of PD commonly found in stator insulation were created on a 6.6 kV epoxy‐mica stator coil. Each PD source was experimentally investigated at a variable excitation frequency in the range of 50–0.1 Hz. PRPD pattern and PD parameters such as integrated charge per cycle and number of discharge pulses per cycle of each discharge source were compared at different frequencies. The comparison suggests that the parameter of each PD source was dependent on excitation frequency. Some discharge sources have shown a distinct variation in their characteristics with excitation frequency. These distinct characteristics are additional information to the existing ones, which will help to correlate PD characteristics with the source of PD in stator insulation. [ABSTRACT FROM AUTHOR]