The Gradient Coating Systems for Electrical Field Control in High-Voltage Generator Stator Windings

Stator windings of high voltage rotating machines (HVRM) operate under combined electrical, thermal, and mechanical stresses throughout their service life. A very special region is the surface of the groundwall insulation outside the stator core, where the electrical stress must transition smoothly from ground potential to the full operating voltage. Due to the electrical field configuration, its electrical stress can reach very high values at the ends of the outer conductive Faraday shield surrounding the groundwall insulation. There are special electrical stress coatings serving to mitigate the electrical field at the end of the outer conductive coating.