1.DC resistivity. The resistivity of copper clad aluminum wire is larger than that of pure copper wire, about 1.5 times that of pure copper wire. When the cathode value is the same, the weight of copper clad aluminum wire is about 1/2 of that of pure copper wire. According to the calculation of the skin effect, when the high frequency is above 5MHz, compared with the acsr conductor of the same cross section, its resistivity is the same. In the use of power cables with a frequency of 50 Hz, the skin effect and proximity effect of copper conductors gradually become prominent above 150mm2. At the same time, due to the continuous development of science and technology, high-order harmonic currents and energy will be injected into the power supply system. , The high-order harmonic voltage of the corresponding frequency is generated on the impedance of the system, causing the voltage waveform to be distorted, increasing the loss of the power supply system, and increasing the heat of the conductor; in addition, the cable amplifies the harmonics and generates overvoltage at the joint. Damage to the cable head. The use of copper-clad aluminum conductors can reduce the AC impedance (resistance) generated by high-order harmonics. In other applications, by increasing the volume of copper in the copper-clad aluminum monofilament and corresponding technological measures, the copper-clad aluminum/copper composite conductor is within the upper limit of the outer diameter of the existing conductor of the same specification and meets the conductor’s DC resistance requirement.
Connection method. The use of copper-clad abc conductors can meet the habit of product selection, design, use, installation, etc. of wires and cables that will be continued for many years, and it is also beneficial to the pressing and tin welding of the cable terminals.
2.Reduce AC resistance. AC resistance is the main basis for the current carrying capacity. According to the principle of skin effect, the current per unit area on the surface of a single wire is larger than the current per unit area of the center of the wire, that is, the center of a large cross-section conductor In the area of a circle formed by the same conductor, the current passing through the center of the circle is smaller than that of the circle. Therefore, it is the most reasonable and economical to use different metals for the center conductor and the circumferential conductor. In addition to the DC resistance and the skin effect, the AC resistance index also has the proximity effect. Compared with the copper conductor with the same DC resistance, after the copper composite conductor is used, the aluminum is in the center of the aac conductor and the copper is on the outer edge; In the composite conductor, the inner layer is copper-clad aluminum and the outer layer is pure copper. Aluminum is not sensitive to the skin effect and proximity effect of copper. At the same time, the copper composite conductor will increase the total cross-section of the conductor by a part, so it also increases the conductor. The surface area of the cable improves the heat dissipation conditions of the cable and increases the heat dissipation area. The thermal conductivity of aluminum is similar to that of copper. Under the same material cost condition, the AC resistance index is much more economical.
3.It has good corrosion resistance: aluminum is more corrosive than copper, but because the copper-clad aluminum material has been completely metallurgized, aluminum is completely covered by copper and will not be in contact with water or air. It can fully achieve the same performance as copper. Copper-clad aluminum/copper composite conductors are also more useful to prevent the cable from being corroded, bruised, or due to tight pressure, poor soldering, and poor contact between the conductor and the terminal, heating and causing the copper layer to fall off and copper and aluminum. A potential difference is formed between metals, which accelerates galvanic corrosion and causes the hidden danger of burning at the end of the cable. For aluminum conductors, especially in coastal areas, the chloride ions contained in the salt spray in the atmosphere will condense on the surface of aluminum, which will easily cause local corrosion around impurities and defects on the surface, forming holes, cracks and micro-batteries, and aggravate the damage of aluminum conductors. corrosion.
4.Low cost and light weight. Compared with the copper core cable with the same technical index, the copper clad aluminum conductor cable can save more than 40% of the cost, and the copper clad aluminum/copper composite conductor cable can save more than 20% of the cost. The proportion of copper clad aluminum wire is only 37%-40% of pure copper wire. When the wire diameter and weight are equal, its length is 2.5 times that of pure copper wire.
5.Good weldability. The copper-clad aluminum wire is concentrically coated with a layer of pure copper, so it has the same solderability as pure copper wire and is convenient for production.