电线电阻与电压降

概述

Engineering ToolBox — 工程技术应用的设计与工程资源、工具和基础信息！

电线电阻决定电流流过导体时损失多少电压。为电路选择正确的线规取决于允许的电压降、导体材料、导线长度和工作温度。本页面涵盖关键公式、常见线径的参考电阻值和实用设计指南。

下载并打印电线电阻图。

关键公式

导体的电阻：

$R = \frac{\rho \cdot L}{A}$

电压降（单相，单向）：

$\Delta V = I \cdot R$

电压降（单相，往返）：

$\Delta V = 2 \cdot I \cdot R$

温度 T 下的电阻：

$R_T = R_{20} \left[ 1 + \alpha \left( T - 20 \right) \right]$

变量

计算器

Conductor Resistivity

AWG Wire Resistance

Resistance vs Temperature for Copper

单位换算器

Interactive Wire Resistance Chart

原始源图

以下原始来源图像予以保留，以免丢失视觉参考资料。当图像包含图表或表格数据时，其提取值已呈现在页面的表格、计算器或交互式图表中；其余图像保留为视觉来源参考。

工程要点

• Voltage drop limits: National electrical codes commonly limit voltage drop to 3 % on branch circuits and 5 % total (feeder plus branch). Always verify local requirements.
• Temperature correction: Wire resistance increases roughly 0.4 % per °C rise for copper. At elevated operating temperatures, apply the temperature correction formula or the chart factor above.
• Aluminum vs copper: Aluminum has about 61 % the conductivity of copper, so an aluminum conductor needs roughly 1.6 times the cross-sectional area to match copper resistance.
• Skin effect: At higher frequencies, current crowds toward the conductor surface, effectively increasing resistance. The values above apply to DC or low-frequency (50/60 Hz) power distribution for solid conductors.
• Parallel conductors: When multiple conductors share a load in parallel, ensure equal lengths and terminations to avoid uneven current sharing.
• Stranded wire: Total cross-sectional area determines resistance regardless of strand count; stranded wire has the same resistance as a solid wire of equal total area.

参考资料

• Original Source — Electrical Wire Resistance