Vacuum Pressure Impregnation

- Oct 05, 2019-

Vacuum pressure impregnation

1. Improve the moisture resistance of the line around the group

Since the pores of the capillary are reduced, the surface is formed into a dense and smooth paint film, and it is difficult for water to immerse into the inside of the insulating layer, so that the moisture resistance is remarkably improved. For example, an E-class insulated small motor without varnish is wet (relative humidity 95%-98% (in the case of 48h, the insulation resistance drops from 40MΩ to 0.2MΩ, while the VPI-treated motor, under the same conditions, The insulation resistance remains above 16MΩ.

2. Improve the electrical performance of the winding

The electrical properties of insulating varnishes are much better than air. For example, 1032 paint has a breakdown strength of 70 to 90 kV/mm under normal conditions, and the breakdown strength of air under standard conditions is only 33 kV/mm. After VPI processing, the windings are bonded together and the air in the insulating layer is removed, thereby increasing the initial free voltage and other electrical properties of the winding.

3. Improve the heat and thermal conductivity of the winding

After insulation treatment, the heat resistance of natural organic fibers is increased from Y to Grade A. The thermal conductivity of the dried insulating varnish is 0.14~0.6W/(m·°C (the epoxy adhesive is 0.2-0.5W/(m·°C (and the thermal conductivity of air is 0.025~0.03W/(m·) °C (, after VPI treatment, the core, the groove and the internal void of the winding are filled with paint, which improves the thermal conductivity of the winding.

4. Improve the mechanical properties of the winding

After the VPI treatment, the winding wires are bonded into a solid whole, thus improving the looseness and wear of the insulation due to vibration, electromagnetic force and thermal expansion and contraction.

5. Improve the chemical stability of the winding

After VPI treatment, the paint film can prevent the insulating material from directly contacting the harmful chemical medium and damaging the insulation performance. The winding can also be insulated to prevent corona and oil.