Assessment of the risk of fatal electric shocks inside a substation and in nearby exposed areas

A simulation approach is elaborated for the risk assessment of fatal electric shocks due to touch and to step voltages that are caused inside and around substations by ground faults. The approach takes into account specific effects of ground faults, depending on their location, and various exposures encountered in practice. A mathematical model that further develops the available approaches is derived. A list of contingencies is analyzed. The total risk level for the substation is determined, considering the exposure inside and around the substation. The body impedance is treated as a random function of the body current rather than an independent random variable, which is a more realistic impedance model according to the available experimental data. The fibrillation threshold is modeled as a random, rather than deterministic, function of shock duration, in accordance with published experimental data. An example shows that the design criteria suggested provide a high degree of safety against potential electric shocks