本标准还提供了直流电的相关数据。
通过应用欧姆定律，可以定义允许的安全曲线
一旦计算出人体阻抗，电压。电气
人体的阻抗取决于许多因素。上述
标准给出了不同的阻抗值作为接触电压的函数
和当前路径。
4.1一般方面：电流对人类的影响
442电气设备| ABB
4保护人类
1SDC010032F001
L1
L2
L3级
N
体育课
1SDC01033F0001
L1
L2
L3级
钢笔N
体育课
（TN-C）（TN-S）
4.2配电系统
接地故障模式和与带电设备接触造成的后果
零件与中性导线布置和
外露导电部件的连接。
为了正确选择保护装置，有必要知道哪个是
工厂的配电系统。
IEC 60364-1用两个字母对配电系统进行分类。
一个字母表示电力系统与地球的关系：
-T：交流系统中，一点直接接地，
通常为中性点；
-I：交流系统中与地面或一点隔离的所有带电部件，
通常为中性点，通过阻抗接地。
二个字母表示外露导电部件之间的关系
安装至地面：
-T：外露导电部件与地面的直接电气连接；
-N：外露导电部件与接地的直接电气连接
电力系统的点。
后续字母（如有）表示中性和保护
导线：
-S：保护功能由与中性点分离的导线提供
导体
-C：作为单个导体（PEN）组合的中性和保护功能
导线）。
考虑了三种类型的配电系统：
TT系统
TN系统

This Standard gives also a related figure for direct current. By applying Ohm’s law it is possible to define the safety curve for the allowable voltages, once the human body impedance has been calculated. The electrical impedance of the human body depends on many factors. The above mentioned Standard gives different values of impedance as a function of the touch voltage and of the current path. 4.1 General aspect: effects of current on human beings 442 Electrical devices | ABB 4 Protection of human beings 1SDC010032F0001 L1 L2 L3 N PE 1SDC010033F0001 L1 L2 L3 PEN N PE (TN-C) (TN-S) 4.2 Distribution systems The earth fault modalities and the consequences caused by contact with live parts, are strictly related to the neutral conductor arrangement and to the connections of the exposed conductive parts. For a correct choice of the protective device, it is necessary to know which is the distribution system of the plant. IEC 60364-1 classifies the distribution systems with two letters. The first letter represents the relationship of the power system to earth: - T: direct connection of one point to earth, in alternating current systems, generally the neutral point; - I: all live parts isolated from earth, or one point, in alternating current systems, generally the neutral point, connected to earth through an impedance. The second letter represents the relationship of the exposed conductive parts of the installation to earth: - T: direct electrical connection of the exposed conductive parts to earth; - N: direct electrical connection of the exposed conductive parts to the earthed point of the power system. Subsequent letters, if any, represent the arrangement of neutral and protective conductors: - S: protective function is provided by a conductor separate from the neutral conductor; - C: neutral and protective functions combined as a single conductor (PEN conductor). Three types of distribution system are considered: TT System TN System