Development trend of insulating paper

Insulating paper is usually a thin sheet material made by depositing plant fiber, mineral fiber, synthetic fiber or their mixture on a paper machine through water or other media.

Insulating paper has high tear strength, low elongation, and good insulation properties, making it widely used as an insulating material in motors, cables, capacitors, and transformers. It is also the main component of insulating materials such as laminates, composite materials, and prepregs.

In recent years, with the development of the electric power industry, modern power generation and transmission equipment have developed towards high voltage and large capacity. With the leap of world science and technology, various high-performance synthetic fibers have been developed and produced and applied in the papermaking industry, such as polyester fiber paper, polyaramid fiber paper, polysulfone fiber paper, polyoxadiazole fiber paper, etc., which have been successfully used in electrical equipment such as batteries, transformers, and capacitors. In particular, the application of aramid insulating paper is the most common and successful.

Due to the special use of insulating paper, it is required to have some characteristics different from other types of paper, mainly mechanical properties, electrical properties, thermal stability, etc.

Mechanical properties

Insulating paper must withstand various external forces during use, such as high mechanical stress caused by high-speed rotation, start and stop, and sudden short circuit in high-voltage and large-capacity generators. Therefore, it is required to have higher mechanical properties, mainly including tensile strength and elongation at break.

Thermal stability

Thermal stability is an important indicator of insulating paper and is the main factor causing low-voltage insulation aging and determining its service life. Under normal working conditions, the electric field strength has little effect on the insulation aging process.

Insulating paper will become brittle due to thermal aging and gradually lose its mechanical and electrical properties if used in a high-temperature environment for a long time.

Electrical properties

Insulating paper is widely used in electrical equipment, so it needs to meet certain electrical performance requirements. The electrical properties of insulating paper refer to its polarization, conductivity, dielectric loss, breakdown characteristics, etc. under the action of an electric field.

The various properties of insulating paper are interrelated and cannot be viewed in isolation. In the process of material selection and development, the advantages and disadvantages of various materials need to be comprehensively weighed.

In addition, to produce insulating paper with good electrical properties, impurities such as metal ions, bubbles, and moisture should be avoided as much as possible during the production process, and the insulating paper should have a high uniformity.