供电线路截面的选择,是设计线路和电工常遇到的实际问题。导线选粗了,造成浪费,很不经济;导线选细了,不能满足供电质量与安全要求,因而合理选择导线十分重要。导线截面的选择,一般应根据机械强度、允许温升、电压损失、截流量等原则来定。由于工矿企业供电线路一般较长,常有几公里至几十公里的长度,所以导线截面应以电压损失条件为主来选择。用电压损失计算导线截面较为复杂,这里以满足线路允许压降和功率因数的提前下,用线路允许负荷矩(以下简称荷矩)来汁算导线截面,较为直接和简便。当已知线路的荷矩和电压 The choice of the cross section of the power supply line is a practical problem often encountered in the design of lines and electricians. Coarse wire selection, resulting in waste, very uneconomical; wire thinner, can not meet the power supply quality and safety requirements, and therefore a reasonable choice of wire is very important. The choice of wire cross-section, the general should be based on mechanical strength, temperature rise allowed, voltage loss, cutoff and other principles to be set. As industrial and mining power supply lines are generally longer, often a few kilometers to tens of kilometers in length, so the wire cross-section should be the main choice of voltage loss conditions. Calculating the conductor cross-section with voltage loss is more complicated. In this case, it is more direct and simple to calculate the conductor cross-section according to the line allowable load moment (hereinafter referred to as the moment) in order to meet the allowable voltage drop and power factor of the line. When known line load and voltage