Recommendations for standardization of voltage level in LVDC networks based on IEC 60479-1 guidelines

In order to standardize the DC (direct current) voltage level in low voltage grids, a study is carried out considering the behavior of the human body against different DC voltage levels. The study is based on an analysis that determines if the amount of body current that flows under specific shock conditions is tolerable or not, keeping the current flow time in account. The body impedance is first calculated for two different DC voltage levels with different skin contact conditions. Possible current paths through the human body are subsequently considered to realize the best and worst-case scenario for human contact with live terminal. A relationship between touch voltage and source voltage is defined considering the grounding methods in DC systems. Using ventricular fibrillation curves, the maximum allowable body currents and the associated flow intervals for human bodies are analyzed for the selected voltage levels. The study makes a step further in addressing the feasibility and safety concerns for the standardization of DC voltage level for low voltage installations.