The application of conductive and stress grading tapes to vacuum pressure impregnated, high voltage stator coils

Conductive tapes are used as a conductive layer on the slot portion of a coil to reduce corona discharges that can occur on coil surfaces. Stress grading corona protection tapes are used on coils at the slot exit region, and they prevent surface discharges at these locations. The use of these commercially available tapes on high voltage coils that are processed using the vacuum pressure impregnation (VPI) method has been developed. Laboratory and factory tests were done to determine the type of tapes to use, the application process, the required process steps, and tape performance after coil processing.