接地系统的选用

接地系统选用不当,将招致一些电气事故的发生,也可能影响电气装置的正常功能,造成不应有的经济损失。现时我国在接地系统的选用上有不少可商榷处,本文就这些问题进行了探讨。结论如下:应谨慎采用TN-C系统;TN-S系统并不比TN-C-S系统更安全;对没有变电所的建筑物以低压供电时,以采用TN-C-S系统较合理,在设有变电所的建筑物内TN-S系统是唯一的最佳选择;TT系统电气设备外壳不接用电源中性点引来的PE线,避免了无等电位联结场所PE线传导故障电压的电击危险,但必须装设RCD;户外无总等电位联结场所都应采用TT系统;我国应扩大IT系统的应用范围。

Selection of Earthing System

Improper selection of earthing system type will cause electric fault and influence normal function of electric equipment. Now there are issues to be worth discussing while selecting earthing type in our country. The paper draws the following conclusions: be careful to using TN-C system; TN-S system is not safer than TN-C-S system; TN-C-S system is suitable to buildings without substation and TN-S system is only choice for buildings with substation; enclosure of electric equipment powered by TT system do not connect PE line from source neutral point, thus avoid fault voltage from PE line at site without equipotential bonding, this electric equipment should be protected by RCD; outdoor site without equipotential bonding should be adopt TT system; application scope of IT system should be enlarged in our country.