Vacuum Pressure Impregnation (VPI) has been used within the electrical industry for many years. VPI was first used as an improved method of forcing resins through multiple layers of wire and insulation. Over the past three decades a majority of original equipment manufacturers have utilized VPI processing to improve the performance and life of industrial duty electric motors. Electrical apparatus treated by the VPI method have proved so successful that it is becoming increasingly specified by the military, steel, and electrical generating companies for severe duty applications.
Vacuum Pressure Impregnation offers several features that help prevent the primary causes of motor and generator failure.
Insulation voids are eliminated through the use of the VPI process. Voids may contain moisture, dust, or other contaminants which lead to a much shortened insulation life. Voids are common place for corona to occur in high voltage applications. The VPI process is the best means of obtaining a void free system.
Premature thermal aging is greatly reduced by the excellent heat transfer properties offered by VPI Systems. Small air pockets in coils, or between coils and core iron, reduces heat transfer. Heat that cannot escape from the coil to the iron will greatly decrease the life of the insulation system.
Vibration is practically eliminated with VPI. An energized coil will move and cause abrasion of insulation unless securely anchored. The complete saturation of insulation and support material results in a solid mass that prevents coil movement.