Insulation Material Inside Transformer
- By : Insulation Materials
Oil paper insulation structure is commonly used in oil immersed transformers in power grid. Paperboard has good insulation materials performance, and the relative dielectric coefficient is about 3.72. The main role of transformer insulating oil is insulation and cooling. Insulating oil can take away the excess heat generated during the operation of transformer. The insulation system composed of insulating paper and insulating oil has excellent electrical performance. Under the action of short-term voltage, its withstand voltage can reach 50-120kv / mm, and the manufacturing process is very convenient.
(1) Transformer insulating oil of Insulation Material Inside Transformer
The original insulating oil is made of paraffin. However, after the aging of transformer, it forms a kind of sludge which is difficult to dissolve, increases the viscosity of insulating oil, and reduces the heat absorption and heat transfer performance. Compared with paraffin, naphthenic oil is very easy to be oxidized, but its products are easy to dissolve in insulating oil, so it is widely used in power system.
The selection of crude oil is a very important part in the manufacturing process of insulating oil. The degree of crude oil refining, refining process and refining workers will have a great impact on the content of various components in the final product. The product insulating oil is a mixture of cycloalkane, alkane and aromatic hydrocarbon in a certain proportion, which has good electrical characteristics, inspiratory property and chemical stability.
Cycloalkanes in transformer insulating oil have good chemical stability and dielectric stability. The change of surrounding temperature has little effect on its viscosity. The molecule is a closed ring chain with tight structure and is not easy to destroy. Moreover, it has low freezing point, wide range of operating temperature, small dielectric loss factor and high dielectric strength, but its oxidation resistance is slightly poor.
(2) Insulating paper of Insulation Material Inside Transformer
The main material of insulating paper is cellulose, which has been discussed in the previous chapter. The main component of cellulose is composed of long-chain sugar and monosaccharide. The content of this kind of cellulose is not pure, because it is difficult to find 100% pure cellulose on wood and other herbs. Generally speaking, the source wood of insulating paper also contains about 15% lignin, cellulose The content is generally about 55%, and about 30% is hemicellulose.
In the manufacturing process of insulating paper, the source wood should be chemically treated first, mainly to remove the majority of lignin and hemicellulose. The commonly used chemical agent is sulfate. After chemical treatment, the cellulose content in the finished insulating paper reaches 80% – 90%.