两种接地系统安全评估标准的区别和联系的分析

Analysis of the Difference and Relation of Safety Assessment Standard of Two Grounding Systems

接地系统的安全评估是人体实际所承受的最大接触电压和跨步电压与最大的安全允许电压进行比较的测试。IEEE Std 80-1986和IEC-471-1都对接地系统的安全评估的标准进行了定义,且两种标准都是根据人体允许通过的电流进行定义,并将其转换为允许的接触电压和跨步电压。本论文通过具体实例,分别利用IEEE Std 80-1986和IEC-471-1计算允许的接触电压,并将实际的接触电压与标准值比较,从而得到IEC-479-1比IEEE Std 80-1986计算相对保守的结论。实际中将IEEE Std 80-1986和IEC-479-1相结合,能达到比较合理的计算结果。

Safety assessment of grounding systems is a testing that the actual maximum touch and step voltages are computed and compared to the maximum allowable(safe) touch and step voltages.IEEE Std 80-1986 and IEC-479-1 are defined the standard of safety assessment of grounding systems.Both standards define safety criteria in terms of allowable body current.The allowable body current is then translated into the allowable touch and step voltages.The paper compares actual touch and step voltages with the standard values which are computed by IEEE Std 80-1986 and IEC-479-1.By means of an example,the conclusion is derived that the IEC-479-1 is more conservative than the IEEE Std 80-1986.We will get reasonable result if we combine IEEE Std 80-1986 with IEC-479-1.