1 Introduction
From 1957 to 1973, China's electrical industry has developed aluminum, aluminum stranded wire, aluminum core insulated wire and cable, aluminum core electromagnetic wire, steel aluminum wire, aluminum core flexible cable and aluminum clad steel wire. Great results, the proportion of aluminum conductors in total conductors increased to more than 60%. In the mid-1990s, under the promotion and promotion of certain organizations, the promotion of copper-core cables has a monopoly on the market. Nowadays, the amount of aluminum conductors has been falling again and again, and it cannot be ignored.
China's copper concentrate supply is less than 30%, and more than 70% of the proportion needs to rely on imports, which is far higher than the external dependence of China's iron ore and oil, and driven by domestic demand, China has become the world's largest copper consumer. In 2006, China's total copper consumption reached 4 million tons, accounting for about 22% of the global supply. At present, most of the copper used for cables is imported from abroad, and foreign monopoly enterprises are rushing to raise prices, resulting in high building electrical costs. On the other hand, China has proven that the reserves of bauxite are 3.7 billion tons. Under such a situation of mineral resources, we are striving to promote the import of copper without paying heavily, instead of using the abundant aluminum resources we own, so that our European counterparts do not understand. Some French cable manufacturers have said that France does not produce copper and is rich in aluminum resources. Therefore, more than 60% of the French power cables use aluminum conductors and are recognized by the French Electric Power Company (EDF).
With the development of science and technology, high-quality, high-tech aluminum materials have been developed, and the current status of global copper-rich aluminum resources, copper parts are now more than three times the price of aluminum (copper about 60,000 yuan / ton, Aluminum is about 17,000 yuan / ton), and the "aluminum" copper has become a natural choice. In the research and application of aluminum conductors abroad, the United States and Canada have developed AA8000 series of electrical grade aluminum alloys as conductor materials. US National Electrical Code NEC2008 version 310.14 stipulates: 8AWG, 10AWG, 12AWG cross-section (equivalent to domestic 8.37mm2, 5.26mm2, 3.332mm2) solid conductor should be made of AA8000 series electrical grade aluminum alloy material; stranded conductor from 8AWG To 1000Kcmil (equivalent to domestic 506.7mm2) should also be made of AA8000 series electrical grade aluminum alloy conductor material. Shandong Wanda Cable Co., Ltd. has specially developed aluminum alloy cables that are compatible with the distribution of civil buildings in accordance with the above specifications.
Definition of aluminum alloy cable
The aluminum alloy power cable is a new material power cable that is invented by AA-8000 series aluminum alloy material as a conductor, using special compression technology and annealing treatment, and chain armor technology.
3.2, the difference between alloy cable and ordinary cable
Alloy cables use AA-8000 series aluminum alloy conductors, while ordinary cables use copper or pure aluminum as cable conductors.
3.3 Why should we promote the use of alloy cables?
At the same volume, the actual weight of the aluminum alloy is about one-third that of copper. According to this calculation, the same weight of the aluminum alloy cable is twice as long as the copper cable, while satisfying the same electrical conductivity. Therefore, the weight of the aluminum alloy cable at the same current carrying capacity is about half that of the copper cable. The replacement of copper cables with aluminum alloy cables can reduce cable weight, reduce installation costs, reduce equipment and cable wear, and make installation easier.
3.4, the advantages of alloy cable than ordinary cable:
Conductive properties:
The conductivity of aluminum alloy is 61.5% of the most commonly used reference material copper IACS, and the current carrying capacity is 79% of copper, which is superior to the pure aluminum standard.
Creep resistance
The alloy material of the aluminum alloy conductor and the annealing treatment process reduce the "creep" tendency of the conductor under heat and pressure. Compared with pure aluminum, the creep resistance is improved by 300%, avoiding the problem of slack caused by cold flow or creep. .
Tensile strength and elongation
Compared with pure aluminum conductors, aluminum alloy conductors have added special components and adopted special processing techniques, which greatly improved the tensile strength and increased the elongation to 30%, making them safer and more reliable.
Thermal expansion coefficient
The coefficient of thermal expansion is used to calculate the dimensional change of the material as the temperature changes. Aluminum alloys have a thermal expansion coefficient comparable to that of copper. Aluminum connectors have been used reliably for copper and aluminum conductors for many years, and most of the electrical connectors used today are made of aluminum, which is especially suitable for aluminum alloys. Therefore, the aluminum alloy conductor is completely identical to the expansion and contraction of the connector.
Strong self-weight bearing capacity
The aluminum alloy improves the tensile strength of pure aluminum. The aluminum alloy cable can support the self-weight of 4000 meters in length, and the copper cable can only support 2750 meters. This advantage is particularly evident when wiring large-span buildings such as stadiums.
Corrosion resistance
The inherent corrosion resistance of aluminum results from the formation of a thin, strong oxide layer when the aluminum surface is in contact with air, which is particularly resistant to various forms of corrosion. The rare earth element added in the alloy can further improve the corrosion resistance of the aluminum alloy, especially electrochemical corrosion. The ability of aluminum to withstand harsh environments has made it widely used as a conductor for cables in pallets, as well as many industrial components and containers. Corrosion is usually associated with the connection of different metals in a humid environment, and appropriate protective measures can be used to prevent corrosion, such as the use of lubricating oils, antioxidants and protective coatings. Alkaline soils and certain types of acidic soil environments are highly corrosive to aluminum, so direct-buried aluminum conductors should be insulated or molded to prevent corrosion. In sulfur-containing environments, such as railway tunnels and the like, aluminum alloys have much better corrosion resistance than copper.
Flexibility
The aluminum alloy has good bending properties, and its unique alloy formulation and processing technology greatly improve the flexibility. Aluminum alloy is 30% more flexible than copper, and its rebound is 40% lower than copper. Generally, the bending radius of the copper cable is 10 to 20 times the outer diameter, and the bending radius of the aluminum alloy cable is only 7 times the outer diameter, which makes it easier to connect the terminals.
Armored feature
Most of the commonly used armored cables in China are equipped with steel tape armor, which has low safety level. When subjected to external destructive force, its resistance is poor, it is easy to cause breakdown, heavy weight, high installation cost, and poor corrosion resistance. The service life is not long. The metal chain armored cable developed by us according to American standards uses aluminum alloy belt interlocking armor, and the interlocking structure between the layers ensures that the cable can withstand strong external destructive forces, even if the cable is under greater pressure. When the impact force is applied, the cable is not easily broken down, which improves the safety performance. At the same time, the armored structure isolates the cable from the outside. Even in the event of fire, the armor layer improves the flame retardant and fire resistance of the cable and reduces the risk factor of fire. The aluminum alloy belt armored structure is lighter than the steel belt armor. It is easy to lay and can be installed without the bridge, which can reduce the installation cost by 20%~40%. Different outer sheath layers can be selected depending on the place of use, making the use of armored cables more widely used.
Tightening characteristics
Considering the volume conductivity, aluminum alloy is not as good as copper, but the conductor we developed not only improved the material properties, but also made great breakthroughs in the process. We used the ultra-conventional pressing technology to make the compression coefficient. It reaches 0.93, and the compression coefficient of the profiled line can reach 0.95, which is the first in China. Through the maximum limit of compaction, it can make up for the deficiency of volumetric conductivity of aluminum alloy, so that the stranded conductor core is like a solid conductor, which obviously reduces the outer diameter of the core and improves the electrical conductivity. Under the same current carrying capacity, the conductor is outside the conductor. The diameter is only 10% larger than the copper cable.
Flame retardant performance
In the event of a fire in a building, heavy smoke and halogen-containing toxins (such as halogenated flame retardants in cables) are fatal killers. The "Electrical Design Code for Civil Buildings" (JGJ16-2008), paragraph 2.4.1, stipulates that "a building with high fire protection requirements for high-rise buildings and important public places shall be flame retardant, low-smoke and halogen-free cross-linked. Vinyl insulated power cable."
The insulation of the armored aluminum alloy cable produced by Shandong Wanda Cable Co., Ltd. is made of low-smoke and halogen-free XLPE (cross-linked polyethylene) material, combined with its unique self-locking armor structure to achieve low smoke and halogen-free resistance. Burning IA grade, the light transmittance of this cable is 99% when burning (standard requirement IA grade light transmittance ≥80%), only a very small amount of smoke is generated, and the secondary injury to the human body is reduced in the event of fire. Conducive to timely evacuation and rescue.
The aluminum alloy crucible of the self-locking armored cable has good heat dissipation and can take away heat quickly. The flame retardant property is excellent, and it can be quickly extinguished after the flame is removed, and other materials are not allowed to be extended. Through the combustion test comparison, the carbonization height of the fire for 40min is only 0.15m, which is far lower than the national standard "Combustion test of cables and cables under flame conditions. Part 33: vertical installation of bundled wire and cable flame vertical spread test type A" (GB) /T 18380.33-2008) The requirements for the carbonization height of the flame retardant cable ≤ 2.50m.
Concerned about surprises
Label: Aluminum conductor Armored cable Bending performance XLPE insulated power cable Direct burial
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