[knowledge] Several commonly used high-temperature insulation material grade

Xiao Bian wants to introduce the grades of high-temperature insulation materials for everyone. I hope everyone can learn more about the relevant aspects.

Insulating materials commonly used by electricians are classified into inorganic insulating materials, organic insulating materials and mixed insulating materials according to their chemical properties. Commonly used inorganic insulating materials are: mica, asbestos, marble, porcelain, glass, sulfur, etc., mainly used as windings for motors, electrical appliances, switches, and insulators. Organic insulating materials include: shellac, resin, rubber, cotton yarn, paper, hemp, rayon, etc. Most of them are used to make insulating paints, covered insulation of winding wires, etc. The mixed insulating material is a variety of molded insulating materials made of the above two kinds of materials and used as a base and a shell of an electrical appliance.

The function of the high-temperature insulation material is to isolate the live parts with different potentials in the electrical equipment. Therefore, the insulation material should first have a high insulation resistance and compressive strength, and can avoid accidents such as electric leakage and breakdown. Secondly, the heat-resisting performance is better, and aging and deterioration are avoided due to long-term overheating; in addition, good thermal conductivity, moisture resistance, lightning resistance, high mechanical strength, and convenient process processing are also required. According to the above requirements, the performance indexes of commonly used insulating materials include dielectric strength, tensile strength, specific gravity, and expansion coefficient.

The compressive strength of high-temperature insulation materials: The higher the voltage applied across the insulator, the greater the electric field force in the charge of the material, and the more likely the ionization collision occurs, causing the insulator to break down. The lowest voltage at which the insulator breaks down is called the breakdown voltage of this insulator. When a 1-mm-thick insulating material is broken down, the voltage kV to be applied is called the dielectric strength of the insulating material, which is simply referred to as the dielectric strength. As insulation materials have a certain degree of insulation strength, various electrical equipment, various safety equipment (electrician's pliers, electroscope, insulating gloves, insulating rods, etc.), various electrical materials, manufacturers are required to provide a certain allowable voltage, said Rated voltage. The voltage applied during use must not exceed its rated voltage to avoid accidents.

Tensile strength of high-temperature insulation materials: The tensile force per unit cross-sectional area of ​​the insulation material can withstand, for example, the glass can withstand a tensile force of 1400 Newton per square centimeter.

The insulation performance of high-temperature insulation materials is closely related to temperature. The higher the temperature, the poorer the insulating properties of the insulating material. In order to ensure the insulation strength, each insulation material has a proper maximum allowable working temperature below which it can be used safely for a long period of time, and if it exceeds this temperature, it will rapidly age. According to the degree of heat resistance, the insulation material is classified into Y, A, E, B, F, H, and C grades. For example, the maximum allowable operating temperature of Class A insulation materials is 105°C. Most of the insulation materials used in distribution transformers and motors are Class A.