One: Performance indicators of insulating materials

    The performance indicators of insulating materials commonly used by electricians are insulation strength, tensile strength, specific gravity, expansion coefficient, etc.

    (1) Withstand voltage strength: When the electric field strength increases to a certain limit, the insulating material will break down in the electric field. The electric field strength of this insulation breakdown is called the dielectric withstand voltage strength (also called dielectric strength or dielectric strength), which is usually expressed in the KV value of the voltage that a 1mm thick insulating material can withstand.

    (2) Tensile strength: the tensile force that the insulating material can withstand per unit cross-sectional area, for example, the glass can withstand 140 kilograms per square centimeter of cross-sectional area.

    (3) Density: The mass of insulating material per cubic meter of volume, for example, sulfur has 2 grams per cubic meter of volume.

    (4) Expansion coefficient: the degree to which the volume of the insulator increases after being heated.

Two: heat resistance grade of insulating material

    (1) Y-grade insulating materials: natural textiles such as wood, cotton, and fibers, textiles based on cellulose acetate and polyamide, and plastics that are easy to decompose and have a low melting point. Maximum operating temperature: 90 degrees.

    (2) Class A insulation materials: Class Y materials that work in mineral oil and impregnated with oil or oleoresin compound glue, insulation of enameled wire, varnished cloth, and varnished wire, and oil-based paint. Asphalt paint, etc. Maximum operating temperature: 105 degrees.

    (3) Class E insulating material: composite polyester film and Class A material, glass cloth, oil-based resin paint, polyvinyl acetal high-strength enameled wire, vinyl acetate heat-resistant enameled wire. Maximum operating temperature: 120 degrees.

    (4) Class B insulation materials: polyester film, mica, glass fiber, asbestos, etc. impregnated with suitable resin bonding, polyester paint, polyester enameled wire. Maximum operating temperature: 130 degrees.

    (5) Class F insulation materials: mica products reinforced with organic fiber materials, glass fiber and asbestos, glass wool cloth, laminated products based on glass fiber cloth and asbestos fiber, and inorganic materials as reinforcement and stone tape reinforcement Mica powder products have good chemical and thermal stability of polyester or alkyd materials, composite silicone organic polyester paint. Maximum operating temperature: 155 degrees.

    (6) Class H insulating materials: mica products without reinforcement or with inorganic materials as reinforcement, thick F-level materials, composite mica, silicone mica products, silicone organic paint, silicone, organic rubber, polyimide composite glass cloth, Composite film, polyimide paint, etc. Maximum operating temperature: 180 degrees.

    (7) Class C insulating materials: inorganic materials that do not use any organic adhesive grade leaching agent, such as quartz, asbestos, mica, glass and electric porcelain materials. Limit working temperature: above 180 degrees.

 Three: Classification of insulating materials

    Insulating materials commonly used by electricians can be divided into inorganic materials, organic insulating materials and mixed insulating materials according to their chemical properties.

    (1) Inorganic insulating materials: mica, asbestos, marble, porcelain, glass, sulfur, etc., mainly used for motor and electrical winding insulation, switch bottom plates and insulators.

    (2) Organic insulating materials: shellac, resin, rubber, cotton yarn, paper, hemp, silk, rayon, most of which are used to make insulating varnish and coating insulation for winding wires.

    (3) Mixed insulating materials: various shaped insulating materials processed from the above two materials, used as the base and shell of electrical appliances.