Wave Propagation Regime to Point to Faulty Feeder in a Mixed Cable-and-Lines Distribution Systems with an SLG Fault

-In radial distribution network with no discontinuities in feeders’ impedances the shape of traveling wave induced by an SLG fault inception will be modeled by multiple refractions and reflections from busbar, fault and loads. The initial propagation zone presents a rigorous polarity disposition of residual currents, with sound residuals having the same polarity. We can determine the minimal sampling frequency necessary to get in that zone the current data indicating faulty feeder. The initial polarity length does not depend on the fault position, its resistance value or on the soil resistivity, and if scrutinized on all feeders it can point out from busbar to fault in systems with laterals. The propagating waves can thus be involved in directional procedures in lines or in cables. Under certain conditions the directional function can be assumed also in mixed networks, with feeders partly in cables and partly in lines.