Update on partial discharge screening tests for stator bars & coils

In 1992 a paper examined evidence of a relationship between measured partial discharge and subsequent voltage endurance of certain stator bars. The PD test method utilizes a higher frequency range than the conventional 30 kHz to 400 kHz and may be more appropriate for the detection of internal voids. More recently there have been other instances where these PD measurements have been useful for identifying stator bars or coils which may have short times to failure on voltage endurance. This paper updates the evidence.