Due to the contradiction copper resource shortages and rapid growth in consumption, in recent years, the price of copper in the worldwide unprecedented skyrocketing. Analysis from a resource perspective, future copper prices will continue to rise, the continuing high price of copper, electrical control and distribution equipment manufacturing enterprises rapidly rising costs, the operating pressure increases rapidly. In this situation, to promote the upgrading of the conductor material. In recent years, the market has emerged with a different process for the manufacture of copper plated aluminum bus, the overlying copper and aluminum busbars, copper clad aluminum busbar, copper and aluminum composite busbar. Copper-aluminum composite bus is an aluminum as a core body, the outer copper clad dual-metal composite material, which is the high chemical stability of the high conductivity of the aluminum-performance, low-cost resource and copper, a lower contact resistance set in one, a new type of low cost energy efficient conductor material, this new type of conductor material entered the market, by the widespread concern and promote the application of electricity control and distribution equipment manufacturing enterprises. This article discusses the copper and aluminum composite bus can meet the requirements of the electric power distribution equipment, the case of copper and aluminum composite busbar electricity control and distribution equipment, and selection principles.
1Copper and aluminum composite bus can meet the requirements of the electric power distribution equipment.
The main requirements of the current-carrying conductor in the electric power distribution equipment ampacity and mechanical strength, specific assessment indicators is the temperature rise limit and the ability to withstand the short-circuit current. The composite material must also ensure that the interfacial bonding strength of the two materials, shearing, punching, bending, no delamination, but also be able to withstand the stress generated in the thermal expansion and contraction destruction. Copper and aluminum composite bus can meet these requirements of the electric power distribution equipment worth studying.
Temperature rise: The temperature rise of the conductor conductivity (current carrying capacity), the cross-sectional area and equipment related to the cooling conditions, select a suitable cross-section can be in the equipment cooling conditions remain unchanged, according to the conductor conductivity.
The dynamic thermal stability: In a three-phase system, to meet the dynamic stability condition is: the stress generated by the electric power to be less than the maximum allowable stress of the material.
The stress generated by the electric power б = M / W
Where: M for short-circuit current generated torque. , M, and the conductive row L proportional to the cube of the distance between the two support points, that is, reducing L can reduce the torque of the electric power generated by the case of the line structure unchanged. W for a conductor cross-sectional coefficient conductor stand up when W = B2h / 6, b is the conductor thickness, h is the conductor width, to increase the conductor cross-section, especially the thickness, i.e. increasing the W, to reduce the electric power generated by moments.
Thus, reducing the distance between the two support points conductive row, to increase the conductor cross-section, especially the thickness, can satisfy the requirements of dynamic stability.
The thermal stability only conductor cross-section, and select a cross-section S by economic current density, and then check the minimum cross-section to meet the thermal stability is much smaller than S.
Busway and low-voltage switchgear products of different specifications of the rated current has been done 30kA, 50kA, 65kA, 80kA, 100kA short circuit test, dynamic thermal stability can meet the requirements.
For copper and aluminum composite conductors, in addition to meet the temperature rise limit and dynamic thermal stability, must also meet the requirements and lifetime requirements, specifically during punching, shearing, bending copper and aluminum is not hierarchical, in the use ofenvironment, thermal expansion and contraction stress will not disrupt the binding between the copper and aluminum, copper and aluminum interface does not produce galvanic corrosion. These problems are associated with the copper and aluminum between interfacial bonding strength, and the interfacial bonding strength has a direct relationship with its manufacturing process, the manufacturing process of different methods, the interfacial bonding strength is different.
Copper and aluminum in the solid state compound, such as the coated welding process, rolling crimping process, pass through the rolling process are mechanical stress, such as copper, aluminum crimp together, interfacial atoms activated by pressure, the formation of atomic bonds, and then subjected to heat treatment diffusion combined into surface binding, but this diffusion limited depth, the composite layer is very thin, the interfacial bonding strength is not high.
Copper and aluminum solid-liquid fusion, i.e. the liquid aluminum is cast in solid brass, copper, aluminum and the melting of the contacting surface of copper and copper and diffusion between the aluminum composite, copper and aluminum formed at the interface layer of thickcomposite layer (about 10 microns), to achieve a higher bonding strength.
Standard power transmission equipment in the power industry with copper clad aluminum busbar "DL/T247-2012 specified in the copper and aluminum bonding shear strength of not less than 35MPa, which is the minimum requirement. Solid-liquid composite copper and aluminum composite busbar usually more than 40MPa. Such as to meet the standard requirements, and in the processing, the combination will not damage the copper and aluminum under the normal use environment, the thermal expansion and contraction stress generated do not damage the copper and aluminum interface.
Shanghai University of copper and aluminum composite busbar HT-TLMY do 0 to 200 ℃, 100 thermal cycle test, testing interfacial shear strength test before and after thermal cycling, the interfacial bond strength not only did not decrease, but increased slightly, whichin this temperature range, eliminating the stress generated by the interface due to the different coefficients of copper, aluminum expansion, while also strengthening the atomic diffusion (Shanghai University of copper and aluminum composite busbar technology research report) between copper and aluminum.
This shows that the use in this temperature range, the expansion and contraction stress destruction not copper and aluminum bonding. Normal use in electrical control, power distribution equipment, the temperature does not exceed 110 ° C. The standard requirements of the short-circuit current in the short-circuit moment within 4s tested on copper and aluminum interface binding was not affected.
In order to verify the long-term thermal fatigue of copper and aluminum composite bus, the Shanghai Electric Cable Research Institute the HT-TLMY copper and aluminum composite bus under the rated voltage of 35kV (Um = 40.5kV) GB/T9327 and below power cable conductor crimpcurrent, DC resistance mechanical connection fitting test methods and requirements "1000 thermal cycle test, each test temperature equilibrium state, the highest temperature, calculate the initial dispersion and average dispersion from the end of the 250 cyclesevery 75 times to calculate the ratio of the resistance ratio until the end of 1000. Eligibility requirements: initial dispersion and average dispersion of ≤ 0.3, the resistance ratio is the ratio of ≤ 2.
The initial dispersion Chinese copper copper and aluminum composite row HT-TLMY ≤ 0. , 23, the average dispersion ≤ 0.15 resistance ratio is the ratio of ≤ 1.29, in full compliance with the standard requirements. (Mechanical industrial electrical materials and specialty cable products Quality Supervision and Inspection Center, Report No. MTN2010-0242). The trial lasted more than six months, fully confirmed the reliability of the use of copper and aluminum composite bus.
Copper and aluminum potential difference, direct contact will produce galvanic corrosion, copper and aluminum composite bus will not produce galvanic corrosion, which is most concerned about the issue. Will not produce the galvanic corrosion, depending on the conditions of generated electrolyte exists between the copper and aluminum, and solid-liquid composite process with a layer of the buffer layer between the copper and aluminum, the transition layer by copper and aluminum solid solution and trace compounds, did not produce, and exposure to air , moisture conditions, therefore, will not produce galvanic corrosion.
A large number of application cases also confirmed that copper and aluminum composite bus fully meet the requirements of the electrical control, power distribution equipment.
Sharp price increases in the price of copper, aluminum row Busway began to increase after the aluminum row galvanized, nickel, tin, surface oxidation problem solving, but the coating is very thin, and the hardness of the soft issue is not resolved, short life, the use of reliablesexual life is poor, the overall effectiveness is not as good as copper and aluminum composite row. Therefore, copper and aluminum composite busbar voltage electrical equipment.
2Copper and aluminum composite bus case
（1）The joint design products
Prototype of China Electrical Equipment Industrial Association, electrical control, power distribution branch organizations nationwide joint design GCK2-4000A surface used in all production of copper and aluminum composite busbar Beijing North China Copper Electric Co., Ltd., through the type test, test all qualified and obtaina certificate of China Compulsory Product certification (CCC). June 16, 2008, the China Electrical Equipment Industrial Association organized experts GCK2 identification of scientific and technological achievements, the experts on the use of copper and aluminum composite busbar current carrying conductors to give a high degree of recognition and evaluation. Feed line counters, cabinets, drawers in the selection of the copper and aluminum composite bus conductor section, weight, cost, and copper busbar contrast the following table.
Seen from the table,
N line, PE line, the same level of bus selection of copper and aluminum composite busbar copper busbar the vertical busbar 2500A and below the copper and aluminum composite bus than copper busbar cross-section of a standard specification, 4000A need to increase by 50% over the current carrying three sides cupboardthe conductor total weight reduction of 44%, the cost decreased by 38.31%.
2010 years in the national box-type design of 24KV substation experimental prototype conductive lined with a row of Beijing North China China Copper Electric Company in copper and aluminum composite. Passing the test.
National Union Busway product design in 2011, the air type 630A-2000A, all intensive 2500A-7200A experimental prototype used by Beijing North China Great Wall Busway production of copper and aluminum composite row Suzhou China copper composite material production, and the test All qualified. In October 2011, to reach the international advanced level in the evaluation of the expert appraisal meeting organized by the China Electrical Equipment Industrial Association.
(2) The other pilot project application
2008 Beijing North China Great Wall Busway on CCX168SJ Series Busway conductors using copper and aluminum composite busbar do in 400A, 1000A, 2500A, 5000A on the full range of type test, CCC certificate. Copper and aluminum composite busbar selection specifications than copper busbar a standard specification, but less than 2500A temperature rise of 8 ~ 10K lower than copper Busway
In 2010-2012, Tianjin Experiment Station, Shandong test standing GGD, GCK, GCS, MNS low voltage switch cabinet has done more than 200 surface 3C safety type test.
(3) project run
Since 2008, North China Great Wall Busway have done more than one hundred copper and aluminum composite row Busway project, such as Phoenix, Beijing, Guangzhou Chiun car Interior Factory (Japanese), MCC roll, Shaanxi, China Construction Bank Qingdao Branch, Shenzhen Wan Jing Plastic Products Factory (Italy owned), Chongqing Technology Company production plant, the Beijing shilipu Xidan Mall, Changchun FAW Bharat Forge Great Wall Industry Corporation of copper and aluminum composite workshop, Changchun FAW Technology Center expansion project row Busway. Has been running for almost five years without any trouble, and reflect good.
Copper and aluminum composite row selection principles
(1) Standard
Plan in accordance with the National Energy Board, led by the State Grid Electric Power Research Institute, Suzhou, copper and other enterprises to participate in formulation of the electricity industry standard "for power transmission equipment copper clad aluminum busbar "DL/T247-2012. The standards promulgated by the National Energy Board, July 1, 2012. The standard requires that the product technical requirements, test methods, inspection rules for the production and sales of the product, to develop the specification.
(2) selection principles
Must be selected to meet the standards in the selection of copper and aluminum composite bus, otherwise it will bring the risk.
1) is not in accordance with the standard test, the product quality is not guaranteed;
2) for 3C certification, do not meet the certification requirements, once discovered, will be fine, even dismantling.
Nationally recognized inspection agency (CNAS) test products in accordance with the standard requirements before they can choose to use the provisions of the China Quality Certification Center on copper and aluminum composite row.
Various regulatory bodies, according to the following requirements: low voltage switchgear for copper and aluminum composite row.
To provide the information requirements: the rows of copper and aluminum composite process, the quality of the product is also different, therefore required to allow enterprises to provide the following information:
CNAS accredited testing laboratory within a year of copper and aluminum composite row type test report, which should be consistent with the power transmission equipment with copper clad aluminum busbar DL / T247-2012 power industry.
Rated voltage of 35kV (Um = 40.5kV) and below power cable conductors with crimp and mechanical connection gold with test methods and requirements "GB/T9327 1000 thermal cycles do test report.
Meet the above requirements may be copper and aluminum composite strip is used for low voltage switchgear. The two test reports to prove that copper and aluminum composite row of the performance parameters to meet the requirements of the power industry standard, and reliability guarantee.
Summary, the success of the research and development of copper and aluminum composite busbar, copper to aluminum section "save the country a lot of shortage of copper for the production of electric power distribution equipment companies to dramatically reduce costs, the country's low-cost energy-saving a new material, and a large number of projects run by trial proved its reliability in the alternative copper busbar save with great advantage, and can be fully used in electric control and distribution equipment.
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