Insulating paper is usually a thin sheet-like material formed by depositing fibers from plant fibers, mineral fibers, synthetic fibers, or their mixtures on a paper machine through water or other media.
Insulation paper has high tear resistance, low elongation, and good insulation properties, making it widely used as an insulation material in motors, cables, capacitors, and transformers. It is also the main component material of insulation materials such as laminated products, composite materials, and pre impregnated materials.
In recent years, with the development of the power industry, modern power generation and transmission equipment have moved towards high voltage and large capacity. With the leap in world science and technology, various high-performance synthetic fibers have been developed and produced and applied in the paper industry, such as polyester fiber paper, polyarylamide fiber paper, polysulfone fiber paper, polyoxadiazole fiber paper, etc. They have been successfully applied in electrical equipment such as batteries, transformers, capacitors, etc., especially the application of aramid insulation paper is the most common and successful.
Due to the special use of insulation paper, it is required to have some characteristics that are different from other types of paper, mainly including mechanical performance, electrical performance, and thermal stability.
Mechanical performance
Insulation paper is subject to various external forces during use, such as being able to withstand high mechanical stresses caused by high-speed rotation, starting and stopping, and sudden short circuits in high-voltage and high-capacity generators. Therefore, high mechanical properties are required, mainly including tensile strength and elongation at break.
thermal stability
Thermal stability is an important indicator of insulation paper and a major factor in causing low-voltage insulation aging, determining its service life. Under normal operating conditions, the electric field strength only has a slight impact on the insulation aging process.
Insulation paper used in high temperature environments for a long time will become brittle due to thermal aging, gradually losing its mechanical and electrical properties.
Electrical performance
Insulation paper is widely used in electrical equipment, therefore it needs to meet certain electrical performance requirements. The electrical performance of insulating paper refers to its polarization, conductivity, dielectric loss, and breakdown characteristics under the action of an electric field.
The various properties of insulation paper are interrelated and cannot be viewed in isolation. In the process of selecting and developing materials, it is necessary to comprehensively balance the advantages and disadvantages of various materials.
In addition, to produce insulation paper with good electrical performance, it is necessary to avoid impurities such as metal ions, bubbles, and moisture as much as possible during the production process, and the insulation paper should have high uniformity.