Vacuum Pressure Impregnation (VPI) is a process that uses vacuum and pressure to seal porous materials with varnish or resin. The process is used primarily for high-voltage motors and generators to fill gaps in materials to create a void free insulation in various devices.
AR EENGINEERING specializes in vacuum pressure impregnation, which is more effective than traditional dip-and-bake methods and is better suited to high voltage motors and generators. Our basic vacuum pressure impregnation motor repair process comprises several steps.
Preheating : We place the equipment in an oven that heats the equipment and allows moisture to evaporate. This helps the resin better penetrate the material.
Vacuum Drying : We remove the equipment from the oven and place it into a vacuum chamber, which removes air and any remaining moisture.
Filling : We fill the chamber with resin, coating the part and filling in all the gaps and pores in the piece of equipment.
Wet Vacuuming : We reduce the vacuum levels and hold it for a set period of time.
Pressure/Soaking : We increase pressure within the chamber using dry air, nitrogen, or other gases. This allows for even deeper penetration of the resin.
Draining : We then vent the pressure, drain the chamber of excess resin, and remove the part.
Curing : Finally, the equipment is placed into an oven to cure the resin.
In traditional impregnation, varnishes can lose up to 50% of their volume in the curing process. The reduced volume leads to air pockets and gaps, making it more susceptible to damage and wear. The vacuum used in a VPI creates a more solid structure that can withstand:
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