Insulation Materials Reliability
Insulation material is one of the most important materials in the transformer, its performance and quality directly affect the reliability of transformer operation and transformer life. Insulation Materials In recent years, the transformer products used in the new insulation material after another.
With the rapid development of science and technology, electrical appliances, transformers and other electrical equipment is increasingly widely used. While the reliability and service life of the transformer is largely dependent on the insulation material it uses. Insulation materials are increasingly engaged in the design and manufacture of transformers.
Insulation material, also known as dielectric, is a high resistivity, Insulation Materials low conductivity of the material. Insulation material can be used to isolate live or different potential of the conductor, so that the current flow in a certain direction. In the transformer products, insulation materials also play a cooling, cooling, support, fixed, arc, improve the potential gradient, Insulation Materials moisture, mildew and protective conductor and so on.
Transformer Insulation material heat resistance grade refers to the insulation material in the transformer to allow the maximum temperature. Insulation Materials If the correct use of insulating materials, you can guarantee the material 20 years of service life. Otherwise it will be based on 8 ℃ law (A-class insulation temperature for each rise of 8 ℃, half of life, B-class insulation is 10 ℃, H level is 12 ℃. This law is known as heat aging 8 ℃ law) Service life. The heat resistance of the insulating material composed of the polymer is lower than that of the inorganic dielectric. Insulation Materials The properties of insulating materials are closely related to their molecular composition and molecular structure.
The four basic parameters of the electrical properties of transformer insulation include insulation resistance, dielectric coefficient, Insulation Materials dielectric loss factor and dielectric strength.
The concept of insulation resistance Insulation material resistance refers to the insulation material in the role of DC voltage, Insulation Materials the pressure is longer, and the line on the charging current and absorption current disappears, only the leakage current through the resistance value / generally specified as the voltage Plus a minute later, the measured resistance value is the insulation resistance value. For high-voltage large-capacity transformers, Insulation Materials the insulation resistance is specified for 10 minutes.
With the increase of temperature, the resistivity decreases exponentially, Insulation Materials because when the temperature increases, the molecular thermal motion increases, the average kinetic energy of the molecule increases, the molecular kinetic energy can reach the activation energy, the ion is easy to transfer.
Moisture is immersed in the dielectric, Insulation Materials increasing the conductive ions, but also promote the dissociation of impurities and polar molecules. So the insulation material decreases as the humidity increases, especially the insulating paper or insulating paperboard insulation resistance decreases more.
In the case of the electric field strength is not too high, Insulation Materials the electric field strength on the ion transfer capacity and the impact on the resistivity is very small. When the electric field strength increases, the ion migration ability increases with the electric field strength, so that the resistivity decreases, when the electric field strength to the dielectric near breakdown, Insulation Materials due to a large number of electrons migration, the resistivity index exponentially.
Due to the heat, the aging of the insulating material is called heat aging. In the heat aging process, the polymer insulation material is often thermal degradation, Insulation Materials low molecular weight or escape. So that the insulation properties of insulating materials and mechanical properties decreased.