Insulating materials The insulating materials mentioned in this article are electrical insulating materials. According to the national standard GB2900.5, the definition of insulation material is :" the material used to insulate the device on the electrical ". The material that stops the current from passing through. It has a high resistivity, usually in the range of 10^9 to 10^22 ω ·m. For example, in a motor, the insulating material around the conductor isolates the turns and the grounded stator core to ensure the safe operation of the motor.

Classification of insulating materials

Classification and performance There are many kinds of insulating materials, which can be divided into gas, liquid and solid. Commonly used gas insulation materials are air, nitrogen, sulfur hexafluoride and so on. Liquid insulating materials are mainly mineral insulating oil, synthetic insulating oil (silicone oil, dodecyl benzene, polyisobutene, isopropyl biphenyl, aryl ethane, etc.) two types. Solid insulating materials can be divided into organic and inorganic two categories. Organic solid insulating materials include insulating paint, insulating glue, insulating paper, insulating fiber products, plastic, rubber, lacquered paint pipe and insulating impregnated fiber products, electrical film, composite products and adhesive tape, electrical laminated products, etc. Inorganic solid insulating materials mainly include mica, glass, ceramics and their products. In contrast, solid insulation materials variety, also the most important.

Different electrical equipment to insulation material performance requirements have different emphasis. High voltage electrical equipment such as high voltage motor, high voltage cable insulation materials require high breakdown strength and low dielectric loss. Low-voltage electrical equipment with mechanical strength, breaking elongation rate, heat-resistant grade as the main requirements.

The macroscopic properties of insulating materials, such as electrical properties, thermal properties, mechanical properties, chemical resistance, climate resistance, corrosion resistance and its chemical composition, molecular structure and so on, are closely related. Inorganic solid insulation material is mainly composed of silicon, boron and a variety of metal oxides, mainly ionic structure, the main characteristics of high heat resistance, working temperature is generally more than 180℃, good stability, atmospheric aging resistance, chemical resistance and long-term aging performance under the action of electric field; But high brittleness, low impact strength, high compressive strength and low tensile strength; Poor workmanship. Organic materials are generally polymers with an average molecular weight of 10 ~ 10, and their heat resistance is usually lower than inorganic materials. The heat resistance of materials containing aromatic ring, heterocyclic ring, silicon, titanium, fluorine and other elements is higher than that of linear chain polymer materials.

The important factors affecting dielectric properties of insulating materials are the strength of molecular polarity and the content of polar components. The dielectric constant and dielectric loss of polar materials are higher than those of non-polar materials, and they tend to adsorb impurity ions to increase the conductivity and reduce their dielectric properties. Therefore, in the process of insulating material manufacturing, we should pay attention to cleanliness and prevent pollution. Capacitors require high dielectric constant to improve their specific properties.