安全接地技術之探討與模擬

A Study on Grounding Techniques for Preventing Electric Shocks

本報告乃探討低壓設備之接地安全問題，並分析故障電流所引起之地電位湧升特性，期能對勞工感電危險之預防有所助益。文中介紹低壓設備之接地，也說明地電位湧升、接觸電壓及步間電壓的觀念， 並比較國內外接地相關的法規。另外，本研究應用 FLUX3D 有限元素法程式模擬發生接地故障時，接地棒及金屬板接地措施的地電位湧升特性，並評估接觸電壓和步間電壓是否滿足人體安全標準。此外，針對接地網接地安全問題，本研究使用一套 CDEGS 程式進行接地故障分析。為了實際瞭解接地特性，本研究亦進行了現場實測，獲得一些接地棒地電位湧升特性和模擬人體感電效應，並與程式計算結果比較。

In this report, grounding safety issues of low-voltage equipment are studied to analyze the characteristics of the ground potential rises due to grounding faults. Thus, practical solutions can be obtained to prevent workers from electric-shock accidents. From these studies, grounding of the low-voltage equipment are introduced and the concepts of the ground potential rise, touch voltage and step voltage are described. Also, the domestic and foreign regulations and codes related to grounding are compared. Then, a finite element program, FLUX3D, is applied to analyze the distributions of the ground potential rises caused by the grounding structures of the ground rods and metal plates during the ground faults. These FLUX3D simulation results can be used to evaluate whether the touch voltage and step voltage satisfy the human body safety regulations or not. Besides, CDEGS is applied to analyze the safety problems of the ground grids. In addition-, measurements are performed in order to practically understand the properties of grounding. Some results of the ground potential rises from ground rods and the effects of the electric shocks on a simulated human body are obtained and compared with the program simulations.