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接地故障模式和與帶電設(shè)備接觸造成的后果
零件與中性導線布置和
外露導電部件的連接。
為了正確選擇保護裝置，有必要知道哪個是
工廠的配電系統(tǒng)。
IEC 60364-1用兩個字母對配電系統(tǒng)進行分類。
一個字母表示電力系統(tǒng)與地球的關(guān)系：
-T：交流系統(tǒng)中，一點直接接地，
通常為中性點；
-I：交流系統(tǒng)中與地面或一點隔離的所有帶電部件，
通常為中性點，通過阻抗接地。
二個字母表示外露導電部件之間的關(guān)系
安裝至地面：
-T：外露導電部件與地面的直接電氣連接；
-N：外露導電部件與接地的直接電氣連接
電力系統(tǒng)的點。
后續(xù)字母（如有）表示中性和保護
導線：
-S：保護功能由與中性點分離的導線提供
導體
-C：作為單個導體（PEN）組合的中性和保護功能
導線）。
考慮了三種類型的配電系統(tǒng)：

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: