Laboratory studies of slot discharges on stator bars

This paper is about experiments carried out on a laboratory stator mock-up comprising 6 stator bars installed in 3 different slots; some of the bars were intentionally damaged in order to reproduce slot discharges. Phase resolved partial discharge (PRPD) patterns, accompanied by simultaneous measurement of capacitance, loss tangent (tan δ) and harmonic analysis were recorded as a function of increasing voltage, from 0 to 16 kV, at steps of 500 V. Another set of results was taken after performing a repair procedure that consists in injecting s/c paint in the stator slots. Results presented here show how slot discharges affect capacitance, tan δ, Q_max, harmonics and PRPD patterns and how all of these quantities are further modified after the injection of s/c paint.