Unsaturated polyester resins for vacuum pressure impregnation

The vacuum-pressure impregnation process has steadily gained acceptance in the manufacture of form-wound and random-wound motors in the past decade. With production experience having demonstrated the effectiveness of this procedure, interest in the process has extended to the repair shop segment of the industry. The varied and unpredictable product mix in a repair shop, however, can create a significantly different set of criteria for choice of a VPI impregnant than those required by original equipment manufacture. Solventless unsaturated polyester resins, with their inherent characteristics for excellent tank stability, high thermal capability and excellent electrical properties, offer an alternative to the repair shop industry that is better suited to its wide range of process and performance requirements.