Insulation Materials Reliability
Insulation material is one of the most important materials in the transformer, Insulation Materials 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, Insulation Materials 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 Insulation materials are increasingly engaged in the design and manufacture of transformers.
Over the past two decades, transformers insulation materials aspects of new products, new technologies, new theories continue to emerge and development, so that the transformer insulation material and its application to form a very important discipline.
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, Insulation Materials cooling, support, fixed, arc, improve the potential gradient, 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. If the correct use of insulating materials, Insulation 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 ℃. Insulation Materials 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. The properties of insulating materials are closely related to their molecular composition and molecular structure.
Transformer insulation materials, many varieties, Insulation Materials according to its form can be divided into gas insulation materials, liquid insulation materials and solid insulation materials.
The concept of insulation resistance Insulation material resistance refers to the insulation material in the role of DC voltage, 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, Insulation Materials the resistivity decreases exponentially, because when the temperature increases, the molecular thermal motion increases, Insulation Materials the average kinetic energy of the molecule increases, the molecular kinetic energy can reach the activation energy, Insulation Materials the ion is easy to transfer.
Moisture is immersed in the dielectric, increasing the conductive ions, but also promote the dissociation of impurities and polar molecules. So the insulation material decreases as the humidity increases, Insulation Materials especially the insulating paper or insulating paperboard insulation resistance decreases more.
The moisture content of the dielectric surface of the dielectric surface is very sensitive to the surface resistance of the ion crystal, and the hydrophobic material of the ionic crystal is more attractive to the water than the cohesion between the water molecules and the continuous water layer on the surface reduces the surface resistance. Insulation Materials So the electrical equipment due to moisture caused by reduced insulation resistance, Insulation Materials resulting in leakage current is too large and damage to equipment
The surface of the dielectric is contaminated by impurities, Insulation Materials and the moisture absorption will cause the surface resistivity to drop rapidly. Insulation resistance of the insulating material is one of the most sensitive parameters reflecting the impurity in the material. Insulation Materials In order to ensure the insulation level of the insulating material, the insulating material plant must strictly control the cleanliness of the production environment in order to measure the impurity content of the insulating material by measuring the volume resistivity in the standard of the insulating material.
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, Insulation Materials so that the resistivity decreases, when the electric field strength to the dielectric near breakdown, due to a large number of electrons migration, the resistivity index exponentially.