What is the electrical conductivity of the cable related to? What factors affect electrical conductivity?

The conductor of the wire and cable is the most important part of the wire and cable. The conductor is the basic element to realize the function of transferring electric charge. Generally speaking, there are two kinds of wire and cable, copper conductor and aluminum core conductor. The latest products also include aluminum alloy conductor wire and cable. . The conduction of wire and cable depends on the conductor of the wire and cable. Let's learn what the conductor of the wire and cable does and what are the factors that affect the electrical conductivity of the wire and cable?

The function of the wire and cable conductor is to transmit current. When the conductor passes through the current, it will generate electrical energy loss and increase the conductor temperature. The conductor temperature rise will increase the conductor resistance, and at the same time reduce the insulation performance. Allowing the working temperature will accelerate the aging of the insulating material and even soften and deform the insulation at the bend of the cable, resulting in shortened cable life or short-term breakdown at the bend of the cable, which cannot meet the requirements of long-term use of the cable; remind everyone to pay attention to the core. The loss of the conductor is mainly determined by the cross-section of the conductor and the volume resistivity of the material. Therefore, the production process must strictly inspect and control the performance indicators of the conductor cross-section and the material.

Factors that affect the electrical conductivity of wires

1. Temperature of wire and cable: The electrical conductivity of metal decreases with the increase of temperature. When the temperature is not very high (close to the melting point) or very low (close to absolute zero), the resistivity and temperature have the following linear relationship: ρ= ρ0[1+α(T-T0)].

2. Impurities in wire and cable materials: The metal contains certain impurities, which will increase its resistance. The influence of impurities on metal resistance depends on the type and content of impurities, and the state of impurities in the metal. Aluminum, antimony, arsenic, phosphorus, nickel, lead, etc. are harmful impurities of copper. When the arsenic content is 0.35% When , the resistivity of copper will increase by 50%; the main harmful impurities in aluminum conductors are silicon and iron.

3. Plastic cold deformation of wire and cable: It is reminded that the elastic deformation of the wire and cable has little effect on the metal resistance, while the plastic deformation increases the resistance. When the cold working deformation exceeds 10%, the resistance increases significantly. For pure metals, the increase in resistance due to cold deformation is generally not more than 4%. The electrical resistivity of the electric round aluminum rod is 0.02801 before drawing. After drawing, it is produced into the electrical round aluminum wire of the required specifications, and the resistivity is 0.028264.

4. Heat treatment (annealing): After the metal is cold-deformed, the tensile strength, yield strength and elasticity increase due to the change of metal crystallization, while the conductivity and elongation decrease. In order to improve the conductivity and flexibility of the cold-drawn copper wire , indicating that the wire is toughened at a certain temperature to achieve the purpose of improving elongation and conductivity, and the resistance can be restored to the level before deformation.

5. Environment for wire and cable use: When environmental factors cause pollution or oxide layer on the metal surface, as well as moisture and oil stains, the metal resistance will increase. When the metal surface is covered with a protective layer of other metals, the resistance can be compounded according to the The size of the original resistivity of the material and the thickness of the coating layer are obtained by calculation. Copper has the effect of promoting aging for some impregnating agents (such as mineral oil, rosin compound impregnating agent, etc.) and vulcanized rubber. In this case, tin can be plated on the surface of the copper wire so that the copper does not directly contact the insulating layer.