Accelerated life testing of high voltage stator coils with enhanced PET-mica insulation system

Abstract

The electrical life of an enhanced PET-mica insulation system used for large rotating electrical machines was investigated by means of voltage endurance (VE) and thermal cycling tests. VE and thermal cycling tests are well understood and industry recognized test methods to qualify new or improved insulation systems. These are reliable test methods for comparing new insulation systems with service proven insulation systems. To develop a life curve, VE testing was performed at three different voltage levels and the acquired data was analyzed using Weibull analysis. A comparison was made between the PET-mica insulation system life curve and those of reference insulation systems. Results indicate that the slope of the VE curve for the new enhanced PET-mica insulation system is changed from previous systems of similar composition, indicating that the life of the insulation system will be comparatively longer and that life and reliability of large motors and generators using this system will be extended.