Slot Conductive Coatings for Electrical Contact Control in High-Voltage Generator Stator Windings

Typical surface resistance range for conductive coatings varies in range 1-20 kΩ/□. Expanded range extends to 0.2-100 kΩ/□.

HVRM stator coils require reliable electrical contact between outer Faraday shield and grounded core to eliminate Partial Discharges (PDs) between coil and stator core. The reliable contact between coil’s outer Faraday is achieved with semiconductive materials and/or fillers in the space between coil and stator core. These filers could or could not that maintains pressure at the coil to core contacts typical filers maintaining pressure at contacts are conductive side ripple springs (SRS) and precured conductive room temperature vulcanized (CRTV) putty.

Over time, two dominant degradation modes are observed: bleaching (PD-driven loss of conductivity), spark erosion (localized arcing/thermal damage under poor contact), also outer

Faraday shield could be damaged mechanically with aggressive environment. Non electrically initiated damage could be converted in one of the two dominant modes.

This paper reviews coating materials and application methods, clarifies diagnostic differences between the three mechanisms, and proposes a practical life-assessment approach based on field experience, endurance testing, and resistivity/visual trending. Repair and maintenance strategies are presented to stabilize affected areas and extend winding service life, delaying major repairs such as full rewinds.