In cable copper raw materials prices, a sharp fall in the number of cable production enterprise profit margins of today, the same as the prices of raw materials is far lower than the copper cable, so “to the aluminum section copper” hot topic has been noisy, so new aluminum cable performance will meet the requirements?
Here, in order to more mature and popular on the market of copper clad aluminum power cables and electrical equipment with wire and cable as an example.
A) dc resistivity, resistivity of copper clad aluminum wire is bigger than pure copper wire, which is about 1.5 times that of pure copper wire resistance value being the same (cross-sectional area is bigger than copper), copper clad aluminum wire weight of about 1/2 of pure copper wire. According to the calculation of skin effect, in more than 50 MHZ frequency, compared with the same cross section of copper conductors, its resistivity is equal. In use of 50 hz frequency of power cable, its copper conductor skin effect and proximity effect in above of 150 was gradually appears outstanding, at the same time due to the industrial and mining enterprises power equipment (such as high frequency furnace, high power motor, etc.) starting, runtime fault, produce higher harmonic current energy will be injected into the power supply system, on the impedance of the system to emit a corresponding frequency higher harmonic voltage, cause the distortion of the voltage waveform, increase the loss of the power supply system, increase the heat conductors.
In addition, cable make harmonic amplification, cable head in overvoltage and joint damage. Using copper clad aluminum conductor will it could reduce the high order harmonic of ac impedance (resistance). On other occasions, by raising the volume of copper in the copper clad aluminum monofilament and corresponding technological measures, make the copper clad aluminum conductor with specifications in current conductor diameter size limit, satisfies the requirement of conductor dc resistance.
B) the copper clad aluminum conductor can meet the current continuation of wire and cable for many years in product selection, design, use, installation of habit, also on the terminal of the cable tight pressure, tin welding.
C) reduce the ac resistance: ac resistance is the main basis of current carrying capacity, according to the principle of skin effect, the surface of the solid conductor, the unit area through a wire current than the center of the circle of unit area by the current. That is to say, the big cross section conductor’s center in the conductor of the same circle area, circle smaller than the circumference of a circle by current, so the center conductor with the circular conductors with different metal composition is the most reasonable and economic.
In addition, influence the ac resistance index except dc resistance and skin effect, and proximity effect, compared with the same dc resistance of the copper conductor, cross section should be adopted for the amplification of copper clad aluminum conductor, within the single conductor, the aluminum in the center of the circle, copper outer circle; Enlarged the copper clad aluminum conductor part due to increased total conductor cross section, and thus increases the surface area of the conductor, to improve the cooling condition of the cable, increasing the cooling area, and the coefficient of thermal conductivity of aluminum and copper, under the condition of equal the cost of materials, the ac resistance index is much more economic.
D) has good corrosion resistance, aluminum than copper corrosion, but because of the copper clad aluminum materials has been completely metallurgical, aluminum coated by copper completely, not exposed by water, air, completely reached and the performance of the copper. For aluminum conductors, especially in the coastal areas, salt fog in the atmosphere of chloride ions will be condensed on the surface of aluminum, easy to cause local around the impurity and defects on the surface of the corrosion, holes, cracks and micro batteries, fuel corrosion of aluminum conductors.
E) the cost is low, the weight is light, compared with the same specifications of copper wire, copper clad aluminum conductor cable can save costs by more than 40%. The proportion of copper clad aluminum wire is only 37% – 37% of pure copper wire, online diameter, under the condition of equal weight, the length is 2.5 times of pure copper wire.
F) good weldability: copper clad aluminum wire because its surface with pericardium was covered by a layer of pure copper, so it is the same as pure copper wire weldability, convenient for production.
Through the above comparison, visible, “to the aluminum section copper” will be more productive, trend obviously, in the future with the advance of “section with aluminum copper, copper aluminum debate is expected to be a winner,” with aluminum section copper cabling industry development trend, at the same time, domestic cable products is expected to achieve product prices are low and stable performance target of qualified products, strengthen the cable industry’s international competitiveness in China, so as to get rid of the notorious “unqualified products”.