Restoration of ground-wall armor of stator bars exposed to slot discharges

Abstract

Slot discharges have been reproduced under well controlled laboratory conditions. Semi-conductive paint was then injected through the ventilation ducts along the side of the bars, without removing the bars or the radial wedges. Partial discharge measurements showed that the slot discharge had completely disappeared from 5 out of the 6 bars, and considerably reduced on the last bar. This last bar was one with tight lateral clearance, thus the paint could not easily infiltrate and restore the damaged area. Partial discharge results, surface observations and a conclusion with respect to the precautions and effectiveness of this correction are presented.