Electrical materials mainly include wires and cables. It has a wide variety of specifications and a wide range of applications, making it the most practical method in electrical engineering to classify based on voltage and usage location. The main knowledge points of this article are: types and applications of wires; The type and application of cables; The types and applications of insulation materials.
1、 Types and Applications of Electric Wires
1. BLX and BLV types: Aluminum core wires, due to their lightweight, are usually used for overhead lines, especially long-distance transmission lines.
2. BX type and BV type: Copper core wires are widely used in mechanical and electrical engineering, suitable for fixed laying of power devices up to 450/750V. However, due to the complex production process of rubber insulated wire BX type compared to polyvinyl chloride insulated wire BV type, and certain chemical components in rubber insulated insulation can have chemical effects on copper, although this effect is slight, it is still a defect, So in mechanical and electrical engineering, it is basically replaced by PVC insulated wire BV type.
3. RV and RX types: Copper core flexible wires are mainly used in movable parts that require flexible connections. The RV type is suitable for household appliances, small electric tools, instruments, etc. with a voltage of 450/750V and below. The allowable working temperature for a long time should not exceed 65 ° C. The RX type is suitable for indoor lighting fixtures, household appliances, and tools with a voltage of 300/500V and below. The allowable working temperature should not exceed 70 ° C
4. BW type: A multi-core flat or circular plastic sheath that can be used for wiring in electrical equipment. It is more commonly used for fixed wiring in household appliances, but the model is not BVV hard wire used in conventional circuits, but RVV, which is a copper core plastic insulated plastic sheath multi-core flexible wire.
2、 Types and Applications of Cables
1. W-type and YJV type: PVC type power cables and cross-linked polyethylene type power cables, which cannot be subjected to mechanical external forces, are suitable for indoor and tunnel cable trays and pipeline laying.
2. W22 and YJV22S: Inner steel strip armored power cables can withstand certain mechanical external forces, but cannot withstand large tensile forces. The YJV22 cross-linked polyethylene insulated power cable allows for a maximum high temperature of 90 ° C for a long time. Its aging resistance and environmental resistance are higher than those of the W22 PVC insulated cable, and it is lightweight, simple in structure, convenient in use, and not limited by drop in laying. For example, in high-rise buildings, hospitals, subways, nuclear power plants, power plants, mines, petroleum, chemical industries, etc., laid indoors, in tunnels, cable trenches, and directly buried underground.
3. ZR-YJFE and NH-YJFE types: Special irradiation cross-linked power cables with flame retardancy, fire resistance, and flame retardancy. The cable can operate at a temperature of up to 125 ° C for a long time and can be laid in suspended ceilings and cable shafts in high-rise buildings, and is suitable for damp places.
4. YJV32 type, WI>ZANYJFE type: inner steel wire armored power cable, low smoke toothless A-grade flame-retardant and fire-resistant power cable, capable of withstanding considerable mechanical external forces. Prefix and subscript changes are used to illustrate the performance and laying location of the cable. The materials used for armor are steel strip, steel wire, etc. The main function of the armor layer is to prevent potential mechanical damage to the cable during laying, to ensure the integrity of the inner protective layer, and to withstand certain external forces. Low smoke, halogen-free, Class A flame-retardant and fire-resistant power cables are mostly used in places with high fire resistance requirements, such as indoor, tunnel, cable trench, and pipeline fixed occasions.
5. LGJ type, LGHJ type: overhead steel core aluminum stranded wire, overhead steel core aluminum alloy wire. In large span high-voltage overhead transmission lines, a high-strength steel stranded wire is required as the reinforcing core of the transmission line conductor, forming a steel core aluminum stranded wire.
6. KW type control cable: suitable for various indoor laying methods in control circuits. For this type of cable, the main considerations are high-temperature resistance and shielding characteristics, as well as oil resistance, acid and alkali resistance, and water resistance. Like wires, the use of power cables should not only meet the special requirements of the site, but also technically ensure that their rated voltage meets the requirements of the working voltage.
3、 Types and Applications of Insulation Materials
1. Insulation paint: mainly composed of synthetic resin or natural resin as the paint base and certain auxiliary materials. It is divided into impregnating paint, enameled wire paint, covering paint, silicon steel sheet paint, and anti-corona paint according to its purpose. Mainly used as insulation material in motors and electrical equipment.
2. Insulation adhesive: Similar to solventless paint, it has a high viscosity and is usually filled with fillers. There are mainly several types of pouring glue, pouring glue, encapsulation glue, etc.
3. Mica products: mainly composed of mica or powdered mica, adhesives, and reinforcement materials. Depending on the composition of different materials, mica insulation materials with different characteristics can be made. Mica products mainly include four categories: mica tape, mica plate, mica foil, and mica glass.
4. Gas dielectric insulation material: In electrical equipment, gas not only serves as insulation material, but also has functions such as arc extinguishing, cooling, and protection. Commonly used gas insulation materials include air, nitrogen, sulfur dioxide, and sulfur hexafluoride (SF6).
5. Liquid insulation material: In electrical equipment, the impregnation and filling of insulation liquid eliminates air and gaps, improves the breakdown strength of the insulation medium, and improves the heat dissipation conditions of the equipment. Commonly used are transformer oil, circuit breaker oil, capacitor oil, cable oil, etc.
6. Laminated products: Laminated products are insulation materials made of paper or cloth as a substrate, soaked in different adhesives, and hot-pressed (or rolled) into a layered structure. Laminated products can be processed into products with good electrical and mechanical properties, as well as characteristics such as heat resistance, oil resistance, mold resistance, arc resistance, and corona resistance.