Do you know where the electrical kraft paper is used?

The insulation paper commonly used in transformers is: electrical kraft paper power cable paper, high voltage cable paper and transformer turn insulation paper.

1) Electrical kraft paper power cable paper: Cable paper is made of sulfate pulp, brand DL08, DL12 and DL17, with thickness of 0.08mm, 0.12mm and 0.17mm respectively, and supplied in rolls. The mechanical and electrical strength of cable paper impregnated with transformer oil can be improved obviously. For example, the electrical strength of power cable paper in air is 6 ~ 9×103kV/m. After drying and dipping in transformer oil, the electrical strength reaches 70 ~ 90×103kV/m. Electrical kraft paper power cable paper has sufficient thermal stability in transformer operation and is usually used for winding insulation and interlayer insulation. Cable paper also includes high voltage cable paper, low voltage cable paper, high density cable paper and insulation crepe paper. High voltage cable paper is suitable for 110 ~ 330kV transformers and mutual inductors with low tangent value of medium loss angle. Low-voltage cable paper is used for insulation of power cables and transformers or other electrical products of 35kV and below; Crepe insulation paper is made of electrical insulation paper after wrinkling processing. It has horizontal wrinkles along it and is pulled apart when drawn. It is often used for wrapping insulation of oil-immersed transformers, such as the head of coils, lead wires and the insulation wrapping of electrostatic shielding devices. The electrical strength of high density cable paper, which is also a kind of insulation crepe paper, is 90% ~ 150% higher than the general crepe paper. High mechanical strength, high electrical strength, good oil resistance, good elasticity, easy to draw, it can replace the lacquer cloth belt as the lead wire, wire connection and the insulation of bending parts.

2) Telephone paper: Telephone paper is also made of kraft pulp, and is commonly used with telephone cables. Its mechanical strength is poor, and it is generally used as turn insulation of wires, layer insulation or covering insulation of conductors.

3) Capacitor paper: Capacitor paper is classified into Class A and Class B according to usage requirements. Class A capacitor paper is used for metallized paper dielectric capacitors in the electronic industry. Class B is mainly used as an interpolar medium for power capacitors. Capacitor paper is characterized by high tightness and thin thickness. Capacitor paper is usually used for current transformers, but less for transformers.

4) Coil insulation paper: Coil insulation paper is used as the backing paper for adhesive paper, which is used for winding insulation tube and capacitive bushing. Its characteristic is that water absorption height is higher than cable paper and lower than impregnated paper. The adhesive paper is divided into one side or two sides of the adhesive (phenolic or epoxy resin) through low temperature curing. Winding insulation tube generally uses single-sided tape, while press tape board uses double-sided tape. In addition, there are also diamond dotted adhesive paper (mesh format dot adhesive paper), used for the interlayer insulation of oil-immersed foil winding coil. It ensures the adhesion between insulation and insulation and foil, enhance the strength and have a better oil permeability after curing.

Cable paper, crepe paper and diamond dotted adhesive paper DDP are commonly used in conventional transformer insulation paper. They are used in transformers as inter-turn insulation, inter-layer insulation, lead binding, etc. Generally, the price difference of various types of insulation paper is not too great.