The several-hour process begins with a prebake cycle to remove any moisture, the component is placed into the varnish chamber, a vacuum is pulled to remove air, varnish is introduced and the varnish chamber is pressurized. Computerized capacitance monitoring insures a 100% solid fill of the component. Considering that a high-grade solventless epoxy base varnish is used to impregnate the component, it will maintain a 100% solid after curing in a bake oven.
The VPI process adds significant value to electrical motor windings to ensure longevity that enhances the life of the insulating materials by preventing ingress of contaminates. Additionally, it adds physical strength to secure electrical windings that are subjected to stresses from electrical in-rush currents.
The VPI process is also used in the manufacturing of nuclear motors. In addition to the electrical components being processed, the frame and remaining mechanical components are also processed. This mitigates any possibility of porosity in castings that are used in a containment area.