Electrically insulating varnished fabrics (varnished fabrics)

Varnishes are flexible materials consisting of fabric impregnated with varnish or some electrical insulating compound. The impregnating varnish or compound forms a flexible film that provides dielectric properties lacquered fabrics.

As a basis for cotton varnishes, use resistant cotton fabrics (percale, etc.). The basis of silk lacquered fabrics are thin natural silk fabrics (excelsior, etc.). For some brands of varnished fabrics (LK1 and LK2), nylon fabrics are used as a basis, which are distinguished by elasticity and increased mechanical strength. For heat-resistant varnished fabrics, flexible fiberglass bases are used - fiberglass fabrics made of electrically insulating (alkali-free) fiberglass.

According to the applied basis, electrical insulating varnished cloth is divided into cotton, silk, nylon and glass.

The main areas of application of varnished fabrics are insulation of grooves and turns in a turn in low-voltage electrical machines, as well as insulation of coils and separate groups of wires in electrical apparatus and devices.Varnishes are also used as flexible electrical insulating seals. To insulate the front parts of the windings of electrical machines and other conductive parts of an irregular shape, a varnished cloth in the form of strips cut at an angle of 45 ° to the base is used. Such tapes have the greatest elasticity.

Cotton, silk and nylon lacquered fabrics can work for a long time in electrical machines and devices at temperatures up to 105 ° C (heat resistance class A). Glass varnished fabrics on oil varnishes (LSMM and LSM brands) also belong to insulation class A (105 ° C) in terms of heat resistance.

Glass varnished fabric, brand LSB on oil-glyftal-bitumen varnish can work for a long time at temperatures up to 130 ° C (class B). This glass lacquer cloth is moisture resistant but not oil resistant.

Escapon glass and varnish cloth FEL impregnated with Escapon varnish. This glass varnish fabric is characterized by increased elasticity and higher electrical characteristics compared to the best cotton varnish fabrics. In terms of heat resistance, the lacquered escapone cloth belongs to class A (105 ° C). Eskaponovaya (similar to cotton varnished fabric LHS) is used as insulation of ducts of low-voltage electrical machines and for insulation of windings of electrical devices operating in air.

Glass fabrics impregnated with silicon varnishes (LSK and LSKL) are characterized by high resistance to heat and moisture. They belong to class H insulation and can work for a long time at temperatures up to 180 ° C, as well as in conditions of high humidity.These glass lacquer fabrics are used as insulation of ducts in electrical machines and devices with a heat -resistant or waterproof design.