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理论上讲,大地既是一个导电体,也是一个无限大的零电位电极。把大地定为零电位并作为参考点,在电力生产技术中也得到广泛应用。电气设备接地的目的,就是根据这一理论,为了在正常和事故以及雷击的情况下,利用大地作为接地电流回路的一个元件,从而将设备接地处固定为允许的接地电位,保护设备和人身的安全。因此,接地技术是我们广大农村电工必须掌握的一门重要的专业知识。1 接地的基本概念1.1 接地的种类。接地按目的区分为保护接地、工作接地、过电压保护接地和防静电接地。电力设备的金属外壳如果绝缘损坏可能带电,为防止这种电压危及人身安全而设置的接地称为保护接地。正常运行需要的接地称为工作接地,如配电变压器低压侧中性点的接地。防雷设备的接地称为过电压保护接地。贮油罐等防止静电危险的接地称为防静电接地。
In theory, the earth is both an electrical conductor and an infinite zero-potential electrode. The earth as a zero potential and as a reference point in the power production technology has also been widely used. The purpose of the grounding of electrical equipment is based on this theory, in order to use the earth as a component of the grounding current loop in the case of normal and accident and lightning strikes, to fix the grounding of the equipment to a permissible ground potential and to protect the equipment and the personal Safety. Therefore, grounding technology is an important professional knowledge that must be mastered by the majority of rural electricians. 1 The basic concept of grounding 1.1 The type of grounding. According to the purpose of grounding, it is divided into protection grounding, working grounding, over voltage protection grounding and anti-static grounding. Electrical equipment, metal enclosure may be charged if the insulation damage, in order to prevent such a voltage endanger the safety and set the ground is called the protective earth. The ground required for normal operation is called working ground, such as the grounding of the neutral point on the low-voltage side of the distribution transformer. Lightning protection equipment grounding known as over-voltage protection grounding. Storage tanks and other static electricity to prevent the grounding called anti-static grounding.