Process quality in medium voltage, global VPI stator rewinds utilizing a high-viscosity thixotropic epoxy resin

Much of the literature currently available to rotating electric machine repair facilities is not designed to present adequate detail for performing and documenting medium voltage stator rewinds. The vacuum pressure impregnation (VPI) method of introducing electrical grade resin into the porous dielectric materials used in the stator winding utilizes a vacuum cycle to remove air from the insulation and a subsequent pressure cycle to push in the resin. High-viscosity resins present a challenge to repair facilities in that typical process cycles have to be modified to ensure adequate penetration.;The purpose of this study is to produce a systematic guide for performing and documenting medium voltage, global VPI stator rewinds based on industry test and processing standards modified for the application of a thixotropic epoxy resin. The guide could serve as a template for any repair facility providing site specific modifications to the impregnation process.