A probabilistic evaluation of human safety near power system installations

During power system ground faults a person's presence in the area of exposure may be exposed to the fault effects and there is a probability that such an exposure will result in a fatal accident. A probabilistic approach to the assessment of a person's exposure to dangerous voltages in the vicinity of power system installations has been proposed. The effects of various random variables on this probability have been studied. Specifically, both the frequency and duration of ground faults,and the frequency and duration of man's presence in the area where an exposure to dangerous voltages may occur, are introduced as random variables. The method can be used for the safe design of grounding system as well as checking the safety adequacy of existing design. The results of calculations give the possibility to find the most dangerous places for persons, which can be present on the area of power system installations or in close vicinity during abnormal system fault conditions.