As we all know, copper cable is a very good wire and cable that can be used in almost any system. However, my country's copper resources are relatively scarce, and it is impossible to achieve full coverage of copper cables. Then let's see if aluminum alloy cables can be used in medium voltage systems.

1. The conductivity of aluminum alloy cables is relatively poor. The conductivity of aluminum cable is only 61% of that of copper cable. Under the same cable cross section, larger resistance will inevitably lead to higher line loss and lower energy utilization efficiency.

2. Aluminum alloy cables have low ampacity. The power grid requires cables to quickly switch the load to the opposite line to ensure uninterrupted power supply to users. However, to achieve high reliability of the power grid, perfect network structure, equipment and lines are essential. The power supply lines in the power grid have high current-carrying capacity, and in addition to their own loads, they should also be able to withstand temporary switching loads. The current-carrying capacity of copper-core cables with the same cross-section is 30% higher than that of aluminum-core cables, which can obviously meet the requirements of urban power supply reliability.

3.Aluminum alloy cable has low mechanical tensile strength. The tensile strength of aluminum cable is only 46% of that of copper cable, allowing 60% lower pulling force than copper cable. A large number of urban distribution networks adopt a cable ring network structure, and the use of cable intermediate joints should be minimized in planning and design. In practice, the laying length of single-core copper cables is generally 600-800m. Considering the same current carrying capacity, the laying length of single-core ordinary aluminum cables is only 500m. Considering the influence of traction, the laying length of single-core aluminum cables is only 500m. 350mm, obviously, due to the low tensile strength and limited length of a single traction cable, a large number of intermediate joints need to be added, which increases the risk of subsequent operation and maintenance.

In addition to the above features, aluminum alloy cables also have weak corrosion resistance, poor high temperature resistance, The high risk of joint failure, the occupation of many channel resources, and the high requirements for wire installation process are the reasons why aluminum alloy wires and cables are not suitable for application and promotion in medium voltage systems.