Relationship between partial discharge pulse height analysis and subsequent voltage endurance of stator bars and coils

A method has been developed for screening stator bars and coils using a particular type of partial discharge (PD) detector. The objective in making PD screening tests was to identify those bars or coils which are more likely to fail on voltage endurance in a relatively short time. The majority of the examples given pertain to a project involving ten hydroelectric generators which had a total of 10800 stator bars. Evidence is presented which suggests that the test method is more sensitive to internal discharges than to those associated with the end grading surfaces