Circulating sheath currents in flat formation underground power lines

Abstract

Three-phase underground power lines can induce voltages and currents in their recover sheaths. The sheath induced currents are undesirable and generate power losses and reduce the cable ampacity whereas the induced voltages can generate electric shocks to the workers that keep the power line. This means that when dealing with three-phase underground power lines, it is very important to know the sheath currents (called circulating currents) that can circulate throughout the sheath of the cables. It is very useful to know their values. The values of the circulating currents depend on different parameters, such as the sheath grounding system, the geometry of the cables, the gap between them, etc. In this work, different geometries of flat configuration underground three-phase power lines have been studied. For each geometry it has been computed the sheath circulating currents in each cable of the power line.