Effect of distances from aerial HV energised conductors have on impressed voltages onto vehicles and machinery

During construction and maintance activities, site personal may need to bring vehicles and/or machinery within close proximity of energised high voltage (HV) overhead lines. These live conductors produce significant electromagnetic fields which will cause electrostatic (capacitive) and electromagnetic (inductive) coupling effects onto conductive items within the produced field. This shall induce a voltage onto the conductive item, which if contacted by a person, can discharge current which has the potential to cause serious harm and/or loss of life. This paper analyses the minimum ‘safe’ distances that conductive items should be located away from aerial energized conductors; where the raised potential is below tolerable limits. Comprehensive CDEGS HIFREQ simulations have been conducted for a variety of HV conductors from 400kV-11kV with adjacent vehicles and machinery at varying distances from said conductors. Minimum ‘safe’ distances for conductive items have been determined and plotted, where induced voltages are below tolerable limits and temporary earth connections may not be required.