小电阻接地中低压共地园林照明采用TN-S的探讨

Discussion about TN-S Application to Garden Lighting of Low-resistance Earthing and MV/LV Common Earthing

中压为小电阻接地系统时,接地故障电流比不接地及消弧线圈接地时要大很多,接地故障电流流经接地体时会产生较大的故障电压。民用建筑内中压与低压一般共用接地,如园林景观照明配电系统采用TN-S系统,中压接地故障电压会沿PE线传至电气设备外壳,可能会产生电击安全问题。通过对此类情况进行分析,提出一些看法供讨论。

When the low-resistance earthing system is applied to the MV system, the earth fault current will he much larger than that when the non- earthing as well as arc suppression coil earthing is selected. The earth fault current flowing through the earth electrodes will generate a large fault voltage. In civil buuldings, the MV system and LV system are generally subject to the common grounding system.For example, TN - S is applied to the garden landscape lighting power distribution system. The MV earth fault voltage will transmit along PE conductor to the electrical equipment enclosure, which might cause safety issues like the electric shock. Based on analysis of these conditions, some opinions are given for discussion.