The reliability of the operation of electric motors depends on the insulation of the windings, which is determined by the quality of the materials used and the correct impregnation of the windings. Impregnation improves the electrical and mechanical properties of the insulation and affects the level of heating, moisture resistance and thermal conductivity.
Winding impregnation consists in filling the pores of insulating materials in order to remove moisture from them. In addition, the impregnation cements the winding turns, preventing their relative movement and abrasion of the insulation of the electric motor being repaired.
Motor windings are impregnated with varnishes or compounds, and then dried. Then the outer surface of the windings is painted with cover enamels and varnishes, as a result of which a hard, smooth film is formed, the thickness of which is 50-60 microns. It protects the insulation from dust, lubricating oils and moisture.
The following methods are used to impregnate the windings :
Impregnation by immersion in varnish is carried out by actually immersing the products in a tank with varnish for its penetration into the winding. Impregnation can be carried out in several stages, until the release of air bubbles from the winding stops.
Compounding is used for pole coils with A class insulation, as well as for the stator coils of high-voltage machines and machines designed to work in high humidity conditions. When compounding, a mass of compound is fed into the boiler under pressure, which fills the space between the wires well.
In addition, the impregnation of the windings is carried out on stands with lacquer supply from below, vacuum-injection method and jet irrigation. The selected method of impregnating the motor windings depends on the winding design and the type of varnish.
