Higher voltage (Medium voltage) Insulation systems have been developed over many years, with a recent interest in newer vacuum pressure impregnation (VPI) insulation systems that have a perception of being newer and better but not with an improvement in longevity or quality. The newer VPI insulation systems today are promoted by some manufacturers and vendors as being better than the older systems that have lasted for the last 50+ years with great success. The main reason for the VPI processing of newer design large motors is for economics. The newer motors are smaller in physical size and have higher temperature rises. The use of VPI in these motors allows the manufacturer to reduce costs for manufacturing purposes… but not necessarily for longevity. This trend has now been incorporated into older machines with the same reasons: for lower costs to process but not necessarily for longer lasting service.