Wire and cable is the basic facility to transmit electrical energy to every home or unit, without which we enjoy a modern life without electricity. However, precisely because of its layout in our work as well as living environment
1. the wire is composed of one or several soft wires, wrapped with a light soft sheath; cable is composed of one or several insulated package wire, then wrapped with a metal or rubber tough outer layer. Cables and wires are generally composed of three parts: the core, insulating sheath and protective sheath. In fact, "wire" and "cable" does not have a strict boundary. Usually the number of cores, small product diameter, simple structure of the product called wire, no insulation called bare wire, the other called cable. Conductor cross-sectional area of larger (greater than 6 square millimeters) called large wire, smaller (less than or equal to 6 square millimeters) called small wire, insulated wire is also known as cloth wire.
2. the cable generally has more than 2 layers of insulation, most are multi-core structure, wound on the cable tray, the length is generally greater than 100 meters. Wire is generally a single layer of insulation, single-core, 100 meters a roll, wireless tray.
3. the diameter of the small called "line"; diameter of the large called "cable".
4. the structure is simple called "wire"; complex structure called "cable".
But with the expansion of the scope of use, many varieties of "cable in the line", "cable in the line". So there is no need to strictly distinguish. In everyday practice, people call the household cloth wire wire, the power cable for short cable.
1. BLX type, BLV type: aluminum-core wire, because of its light weight, usually used in overhead lines, especially long-distance transmission lines.
2. BX type, BV type: copper-core wire is widely used in mechanical and electrical engineering, suitable for 450/750V and below the fixed laying of power installations, but because of rubber-insulated wire BX type production process than PVC insulated wire BV type complex, and rubber insulation of certain chemical components in the insulation will have a chemical effect on copper, although this effect is slight, but is still a defect, so in Electrical and mechanical engineering is basically replaced by polyvinyl chloride insulated wire BV type.
3. RV type, RX type: copper-core flexible wire is mainly used in the flexible connection of the movable parts of the RV type for 450/750V and below household appliances, small electric tools, instruments and meters, etc., the long time allowable working temperature should not exceed 65 ° C. RX type for 300/500V and below indoor lighting, household appliances and tools, etc., the allowable working temperature should not exceed 70 °C.
4. BVV type: multi-core flat or round plastic wire, available in electrical equipment wiring, more often found in household appliances fixed wiring, but the model is not the conventional line with BVV hard wire, but RW, for copper-core plastic insulation plastic sheathing multi-core flexible wire. For example, general household and office lighting usually use BV type or BX type PVC insulated or rubber insulated copper core wire as the power connection line; electromechanical engineering site welding machine to welding pliers in the connection line more RV type PVC insulated copper core flexible wire, this is because the welding position is not fixed, more mobile.
1. VV type, YJV type: PVC type power cable, cross-linked polyethylene type power cable, can not be subject to mechanical external forces, suitable for indoor, tunnel bridges and pipelines laid in the pipeline. For example, Pudong New Area Dalian Road tunnel laid across the Huangpu River power cable but the use of YJV type copper core cross-linked polyethylene insulation polyvinyl chloride sheathed cable, because the cable will not be subject to mechanical external forces in the tunnel, and does not require large tensile forces.
2. VV22 type, YJV22 type: inside the steel belt armored power cable, can withstand certain mechanical external force, but can not withstand large tensile force. Cross-linked polyethylene insulated power cable YJV22 type long-term allowable maximum temperature of 90 ° C, aging resistance, environmental resistance than PVC insulated cable VV22 type high, and has a light weight, simple structure, easy to use, laying is not restricted by the drop. Such as in high-rise buildings, hospitals, subways, nuclear power plants, power plants, mines, petroleum, chemical and other laying in indoor, tunnel, cable trench and direct burial underground laying.
3. ZR-YJFE type, NH-YJFE type: flame retardant, fire-resistant and other special irradiated cross-linked power cable, the highest long-term allowable working temperature of the cable up to 125 ° C, can be laid in the ceiling, cable shaft in high-rise buildings, and suitable for wet places. Flame-retardant cable should have flame retardant properties, in order to extinguish, reduce or inhibit the burning of materials, the need to add commonly used materials and engineering equipment 11 substances or treatment of materials, usually in the material with flame retardants, so that the material has the performance of stopping or retarding the spread of flame when burning. That is, burning on an open flame, and automatically extinguished after leaving the fire for a period of time. Currently there are four grades A, B, C, D, generally commonly used C grade.
Fire-resistant cable is characterized by the ability to conduct electricity when the cable is burning or even for a period of time after burning, and is mostly used f relatively important working environments, such as on warships. Flame-resistant cables can also have the performance of flame retardant, flame retardant cables but no fire-resistant performance.
4. YJV32 type, WI>ZANYJFE type: inner steel wire armored power cable, low smoke and halogen-free class A flame retardant and fire-resistant power cable, can withstand considerable mechanical external force, with the prefix and subscript changes to illustrate the performance of the cable and can be laid places. The material used for armored is steel belt, steel wire, etc. The main function of the armored layer is to prevent the cable from mechanical damage that may be encountered during laying, to ensure the integrity of the inner sheath and can withstand certain external force. Low-smoke halogen-free A grade flame retardant and fire-resistant power cables are mostly used in occasions with high fire protection requirements, such as indoor, tunnel, cable trench and pipeline and other fixed occasions.
For example, low-smoke halogen-free A fire-retardant irradiated cross-linked power cable WI>ZANYJFE type, whose maximum allowable working temperature can reach 125 ° C, suitable for laying in the cable shaft, ceiling of high-rise buildings. The submarine cable from Zhoushan to Ningbo uses type VV59 copper-core PVC insulated PVC sheathed inner thick steel wire armored cable, because it can withstand large tensile forces, has anti-corrosion capability and is suitable for laying in water.
5. LG type, LGHJ type: overhead steel-core aluminum stranded wire, overhead steel S aluminum alloy conductor. In the large block distance of high-voltage overhead transmission lines, a high-strength steel strand is required as the reinforcement core of the transmission line wire, consisting of steel-core aluminum strand.
Steel-core aluminum alloy conductor than steel-core aluminum stranded wire has a large tensile strength, light weight, good arc sag characteristics, etc., in the line laying can reduce the height of the tower, . Increase the erection spacing, save and reduce engineering investment,. More applicable r-large length, large span, ice and snow storms and other areas of the transmission line.
At present, the domestic and foreign transmission system in the phase of the conductor is still mainly round concentric stranded steel-core aluminum strand, steel-core aluminum strand in the international application of more than 100 years of history and mature experience. Domestic has formed a set of strict specifications from product to engineering design, construction and operation and maintenance, the maximum cross-section of 1000mm2. has been used in AC 1000kV and DC ± 800kV ultra-high voltage transmission lines.
For example, the 1000kV Jinnan ~ Nanyang ~ Jingmen UHV AC test demonstration transmission line project, which was put into operation in 2009. is the first UHV project in China and the first domestic transmission line project using single-circuit, eight-split steel-core aluminum stranded wire design. Jin southeast ~ Ruzhou section of the line length of 34.219km, a total of 67 towers (N244 ~ N340). Line conductors use two forms of eight split steel-core aluminum strand, N255 ~ N266 for the macaque reserve, using 8XLGJ-630/45 type, the rest of the section using the 8XLGJ-500/35 type. For example, the Yunnan-Guangdong UHV DC transmission project put into operation in 2010 is the world's first Shi 800kV UHV DC transmission project, and is also China's UHV DC transmission independent demonstration project.
6、KVV type control cable: It is suitable for indoor control circuit of various laying methods. For this type of cable, the main consideration is the high temperature resistance and shielding characteristics and oil resistance, acid and alkali resistance, water resistance. As with electric cables, the use of power cables in addition to meeting the special requirements of the place, from a technical point of view, should mainly make its rated voltage to meet the requirements of the working voltage.
Electrical materials have now derived new fire-resistant cables, flame retardant cables, low-smoke halogen-free / low-smoke low-halogen cables, termite / rat-resistant cables, oil / cold / temperature / wear-resistant cables, mining cables, thin-walled wires and other products. For example, 220V wires used for household appliances, 380V cables for general industrial enterprises, and 500kV, 220kV, 110kV ultra-high voltage and high-voltage cables used for transmission and distribution lines. For example, flame retardant control cables are suitable for control, monitoring circuits and protection lines with special flame retardant requirements for AC rated voltage 450/750V and below, as control wiring between electrical equipment.
Wire and cable market status
In the past decade, China's wire and cable industry has made great strides in development, and with an industry output value of 1.1 trillion once surpassed the United States to become the world's first. The current global wire and cable market size has exceeded 100 billion euros, and within the global wire and cable industry, the market size of Asia accounted for 37%, the European market close to 30%, the American market accounted for 24%, the other markets accounted for 9%. With China's power grid smart grid construction and the corresponding transformation and upgrading of the agricultural network project continues to promote the actual construction phase has arrived, the development of domestic wire and cable industry has also ushered in the development opportunities. At present, China's cable industry by the technical strength is not very strong, in many aspects is not as good as similar foreign products.
1. regional: Asia Pacific, South America, the Middle East and Africa and other developing countries concentrated in the region because of the accelerated industrialization and transmission and distribution network expansion needs to improve and become the fastest growing several regional markets for wire and cable market. Among them, the Asia-Pacific market will become the largest demand for regional markets.
2. the scope of end-use applications: infrastructure construction, industry and renewable energy are the three main end-use markets.
3. demand: the wire and cable market demand is expanding, for the relevant wire and cable manufacturers, only firmly occupy the distribution market, in order to strengthen the foundation of high-end product development; have good value for money wire and cable products, in order to gain market and user favor.
