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Life And Improve The Reliability Of Power Supply Key
- Sep 01, 2017 -

At present, the most widely used power transformers are oil-immersed transformers and dry-type resin transformers. The insulation of power transformers is the insulation system composed of transformer insulation. It is the basic condition for the normal operation and operation of transformers. Insulation material (ie oil paper or resin, etc.) determined by the life.

Practice has proved that most of the transformer damage and failure are caused by damage to the insulation system. According to statistics, due to various types of insulation failure occurred in the accident accounted for more than 85% of all transformer accidents. The normal operation and attention to the maintenance of the management of the transformer, the insulating material has a very long service life. Therefore, the protection of the normal operation of the transformer and strengthen the reasonable maintenance of the insulation system, to a large extent can ensure that the transformer has a relatively long service life, and preventive and predictive maintenance is to improve the life of the transformer and improve the reliability of power supply key The

In the oil-immersed transformers, the main insulating materials are insulating oil and solid insulation materials, paperboard and wood blocks, etc. c so-called transformer insulation aging, that is, these materials are affected by environmental factors decomposition, reduce or lose the insulation strength.

Solid paper insulation is one of the main parts of oil-immersed transformer insulation, including: insulating paper, insulation board, insulation pad, insulation roll, insulation banding, etc. The main component is cellulose, chemical expression (C6H10O6) n, N is the degree of polymerization. Generally, the degree of polymerization of the new paper is about 1300, and when it reaches about 250, the mechanical strength has been reduced by more than half, and the degree of polymerization at the end of life is 150 to 200. After the aging of the insulating paper, the degree of polymerization and tensile strength will be gradually reduced, and generate water, CO, CO2, followed by furfural (furan formaldehyde). Most of these aging products are harmful to electrical equipment, will reduce the breakdown voltage and volume resistivity of insulating paper, the dielectric loss increases, the tensile strength decreases, and the metal material in the equipment is very corroded. Solid insulation has irreversible aging properties, and its mechanical and electrical strength degradation can not be restored. The life of the transformer depends on the life of the insulating material. Therefore, the oil-immersed transformer solid insulation material should have good electrical and mechanical properties, and the performance of the transformer is slow, that is, the aging characteristics are good.

Insulating paper fiber material is the most important insulating component material in oil-immersed transformers. The paper fiber is the basic solid tissue component of the plant. The atoms of the constituent material molecules have positively charged nuclei and negatively charged electrons running around the nucleus. Conductor is different from the insulating material in almost no free electrons, insulators in the very small conductance mainly from the ion conductivity. The cellulose is composed of carbon, hydrogen and oxygen, so that there is a potential for the formation of water due to the presence of hydroxide in the molecular structure of the cellulose, so that the paper fibers have water-containing properties. In addition, these hydrogen atoms can be considered to be surrounded by various polar molecules (such as acid and water), they are combined with hydrogen bonds, making the fiber vulnerable to damage: the fiber often contains a certain proportion (about 7% ), These impurities include a certain amount of water, because the fiber was colloidal nature, so that the water can not be completely removed. This also affects the performance of paper fiber.

Polar fibers are not only easy to absorb moisture (moisture to make strong polar media), and when the paper fiber absorbs water, the interaction between the hydroxyl force weakened, the fiber structure is unstable under the conditions of mechanical strength sharp deterioration , Therefore, the paper insulation parts are generally dried or vacuum dry treatment and immersion paint or insulating paint before use, the purpose of dipping paint is to keep the fiber wetting to ensure that it has a higher insulation and chemical stability and High mechanical strength. At the same time, the paper is sealed after the paint can reduce the absorption of water on the paper to prevent oxidation of materials, but also to fill the gap to reduce the insulation performance may be possible, resulting in partial discharge and electric breakdown of the bubble. But some think that after the dip and then dip oil, there may be some paint will slowly dissolve in the oil, affecting the performance of oil, the application of such paint should be sufficient to note.

Of course, the different properties of different fiber materials and the same composition of the different quality of fiber materials, the impact of the size and performance are different, such as the highest fiber content in cotton, cannabis fiber is the most solid, some imported insulating paperboard because of its processing and processing Performance is better than some of the domestic materials, such as cardboard. Transformers Most insulating materials are insulated with various types of paper (such as paper, paperboard, paper pressure molding, etc.). Therefore, in the transformer manufacturing and maintenance of a good choice of fiber materials, insulation paper material is very important. The special advantages of fiber paper is practical, low price, easy to use, in the temperature is not high when the molding and processing simple and flexible, and light weight, moderate strength, easy to absorb impregnated materials (such as insulating paint, transformer oil, etc.).