Vacuum Pressure Impregnation Plant
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.
The Vacuum Pressure Impregnation Process
AR Engineering 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.
Impregnation Types:
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Varnish Impregnation
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Oil Impregnation
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Casting Impregnation
The Benefits of VPI
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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Leaks
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Cracks
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Corrosion
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Moisture