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Several aspects of the development of power cables in which copper and aluminum replace each other

2 years ago 1603 0 News



The Mutual Substitution of Copper and Aluminum in Cable Development


Aluminum alloy power cable is AA8030 series of aluminum alloy for the conductor, the use of a special pressing process and annealing and other advanced technology to create a new type of material power cable. 

The copper cable is now used by the public as the copper material for the conductor of the power cable.

Aluminum alloy power cable


I. Introduction


With China's economy in the development of a new normal, aluminum alloy cable in the electrical market occupies a certain share. 

Related Media and enterprises put forward in the field of the power cable to promote "aluminum on behalf of the copper", and crown the future "development direction" to solve the shortage of copper resources, with "strategic initiatives." 

This paper mainly on the aluminum alloy cable and copper cable in eight aspects of horizontal comparison, combined with practical application, rational and prudent view of copper and aluminum alternative.


Ⅱ. Copper and Aluminum Resources Comparison


China's relative shortage of copper resources is an objective fact, but the aluminum resources are not rich. 

The so-called "aluminum-rich copper" is not in line with national conditions misleading publicity. 

As we all know, the domestic aluminum processing industry due to a serious excess capacity has long been included in the national restrictions on the elimination of backward production sequences. 

Domestic bauxite aluminum and silicon ratio are low, alumina production costs are high. 

Over-exploitation of aluminum ore makes the domestic storage and storage ratio only 6.6 years, much lower than the oil industry's 10 years of storage and production ratio, obviously, reserves can not meet the rapid economic growth needs. 

However, in order to maintain a huge aluminum production capacity, must be a large number of overseas procurement of aluminum resources, is expected that the "thirteenth five" aluminum overseas dependence will reach more than 60%. 

In the long run, there is a systematic risk of a shortage of aluminum resources. 

In contrast, copper is 100% recyclable metal, and the domestic storage and storage ratio is still 16 years, if the current foreign exchange reserves and low-cost copper advantage, a large number of foreign copper mining resources, "possession of copper in the country" no doubt More prominent strategic significance.


Ⅲ. Aluminum Versus Copper Cables


Aluminum alloy cable is based on ordinary aluminum to add trace elements as a conductor cable form, although the aluminum cable upgrade version, compared with the copper cable is still a significant disadvantage.


1 Aluminum Alloy Cable Conductivity is Poor

Aluminum alloy cable conductivity is only 61% of copper cable. In the same cable section, the large resistance will inevitably lead to high line loss, and reduce energy efficiency. 

Under the same current carrying capacity, the resistivity of the aluminum alloy cable is always slightly larger than that of the copper cable. 

To the load current 380A, the use of hours 4500h, operating life of 30 years, for example, copper cable section if the use of 150mm 2, the aluminum alloy cable section to be 240mm 2, the resistivity of the two were 0.148 / km and 0.150 / km.

Consumption of 288495kwh / km and 292410kwh / km, the whole life cycle of the two energy consumption difference of 117450kwh / km. 

Obviously, the life cycle of aluminum alloy cable loss is too large, away from the national "energy-saving emission reduction" direction of development.


2 Aluminum Alloy Cable Carrying Low Flow

City power supply reliability requirements of 99.99%, the core area to reach a higher level of 99.999%. 

As the city cable network uses a ring network structure, the case of failure within a short time to protect the action, quickly cut the load to the opposite side of the line to ensure uninterrupted user power supply. 

But to achieve a high-reliability grid, and improve the network structure, excellent equipment and lines are essential. 

The power supply line in the power grid must have a high current carrying capacity, in addition to its own load but also bear the temporary switching load. 

The same section of the copper cable as the aluminum alloy cable carrying capacity higher than 30%, obviously better meets the requirements of urban power supply reliability.


3 Aluminum Alloy Cable Mechanical Low Tensile Strength

Aluminum alloy cable tensile strength is only 46% of copper cable, allowing traction than copper cable 60% lower. 

The urban distribution network uses a large number of cable ring network structures, planning, and design to minimize the use of cable intermediate joints. 

In actual use, a single copper cable laying length is generally in the range of 600 ~ 800 meters. Considering that under the same current carrying capacity, the laying length of a single ordinary aluminum cable is only 500 meters. 

Considering the impact of traction, the laying length of a single aluminum alloy cable is only 350 meters. 

Obviously, low tensile strength will inevitably lead to a single traction cable length is limited, the need to add a large number of intermediate joints and increase follow-up operation and maintenance risks.


4 Aluminum Alloy Cable Corrosion Resistance is Weak

Corrosion of cable conductors is mainly electrochemical corrosion of metal, that is, the metal surface of the original battery or stray current interference caused by the role of electrolytic batteries. 

Aluminum alloy cable in the production process in order to improve the creep resistance by adding magnesium, copper, zinc, silicon, and other elements, and increase the heat treatment process. 

As the cable operating conditions are complex, in the electrolyte-containing environment, the lower electrode potential of aluminum and other metal elements added to the electrode is poor, resulting in the current path, pitting corrosion and crevice corrosion, and other electrochemical phenomena. 

The aluminum alloy cable heat treatment process is also likely to cause the conductor surface physical state to be not uniform, increasing the possibility of electrochemical corrosion, followed by stress corrosion cracking and intergranular corrosion.


5 Aluminum Alloy Cable High-Temperature Performance is Poor

With a copper melting point of 1080 and an aluminum melting point of only 660, apparently, the copper conductor is a better choice for fire-resistant cables. 

In the event of a fire, the central ambient temperature can rise above 750, and the cable must be able to maintain the basic function of the power supply to build a life support line. 

Obviously, when the fire temperature is higher than the melting point of aluminum and aluminum, no matter what kind of insulation measures, the cable conductor will melt in a short time, loss of conductive function, which seriously affects the fire evacuation of personnel.

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