Isolationspapier

Isolationspapier, insulating paper, is a cellulose-based sheet material used to insulate electrical components and devices. It is typically produced from chemically pulped wood fibers (kraft) and manufactured as thin sheets or plies. The paper can be used dry or impregnated with insulating liquids or resins to increase dielectric strength and moisture resistance. Common forms include dry insulation papers for mechanical separation and interleaving layers within windings, and oil-impregnated papers used in transformers as part of the winding insulation system. In some applications, papers are combined with other materials to form composite insulation suitable for higher temperature service.

Key properties are dielectric strength, moisture uptake, thermal stability, and mechanical strength. Dielectric strength indicates the voltage withstand capability, which is highly sensitive to moisture content. Therefore drying and proper impregnation are critical. Thermal classes or ratings describe the maximum operating temperature of the insulation system; transformer papers are often specified for high-temperature classes. Aging behavior and chemical compatibility with impregnating media are also important.

Manufacture: sheets are formed from pulp, pressed, dried, and sometimes treated with oils or resins to reduce porosity and improve barrier properties against moisture and oxygen.

Applications: insulating papers are used in transformers, motors, generators, cables, and other electrical equipment to separate conductors, provide dielectric insulation, and improve mechanical separation of windings. They are selected for dielectric strength, aging resistance, and compatibility with impregnating media.

Standards: products meet national and international standards governing dielectric strength, moisture content, aging, and compatibility with oils or resins; manufacturers provide datasheets with test values.