Distance relays ideal tripping characteristic in presence of directly connected load to transmission lines

This paper discusses the impact of a directly connected load to transmission lines, without switching and protective facilities, on distance relays at the line ends, by means of presenting the measured impedance at the relaying point and the distance relay ideal tripping characteristic. The measured impedance at the relaying point is affected by several factors, including the line structural and pre-fault loading conditions, and specially the fault resistance. In the presence of a directly connected load to the line, in addition to its connection point, its type affects the measured impedance at the relaying point. The variation of the measured impedance due to changes in the concerning parameters would be investigated.