When selecting a wire harness, the material of the core wire is the key to determining the performance of the wire harness. We commonly have copper core wire harnesses and aluminum core wire harnesses. Aluminum core wire harnesses are generally used for low-cost projects and temporary electricity use, and cannot be used for a long time. The copper core wire harness is recognized as a wire harness with high safety and reliability, and can be used for a long time. Why does this difference occur? This is determined by the properties of aluminum itself.
(1) The surface of aluminum wire is easily oxidized in the air. Without special treatment, aluminum oxide films will form within seconds on aluminum wires exposed to air. Even though its thickness is only a few microns, it has a high resistivity, which forms a large film resistance and causes overheating, which becomes a safety hazard.
(2) High expansion coefficient. The expansion coefficient of aluminum is as high as 23×10-6/℃, which is 39% larger than that of copper. 97% larger than iron. When the aluminum wire is connected with these two metal conductors and passes electric current, the connection point heats up due to the contact resistance. All three conductors will expand thermally, but aluminum expands more than copper and iron, so the aluminum wire will be squeezed. When the line is powered off and cooled, the flattened aluminum wire cannot be completely restored to its original state, which will cause voids and air to enter. The aluminum oxide film formed by air will increase the contact resistance. When the power is turned on next time, the heat will be more severe, which will further deteriorate the situation. In severe cases, it may cause a fire due to abnormally high temperature.
(3) Electrolytic corrosion is prone to occur. If there is an acidic or alkaline liquid between two metals with different potentials, the two metals will form a local battery. The potential of aluminum is -0.78V, while that of copper is -0.17V. This local battery is formed when there is salty moisture between the aluminum conductor and the copper conductor. Ionization will corrode the aluminum conductor with low potential and increase the contact resistance.
(4) It is easily corroded by hydrogen chloride. Another problem may arise for PVC insulated aluminum core wire harnesses, cables. PVC insulation will continuously decompose hydrogen chloride gas, especially when the line temperature exceeds 75 ℃, the original hydrogen chloride stabilizer of PVC insulation can no longer prevent the formation of hydrogen chloride. Hydrogen chloride will corrode aluminum wire, increase contact resistance and fire hazard.
Therefore, copper core wire harnesses have long occupied the mainstream position of the market, while aluminum core wire harnesses are rare.
TXGA is a leader in wire harness manufacturers, providing customers with wire harness products and technology-oriented customized services with high-quality products, considerate services and reasonable prices. Purchase professional wire harnesses and enter TXGA [Product Center].
