Measured impedance at source node of a distribution feeder with DG unit for inter phase faults

Distance protection is not utilized in distribution networks, unlike the transmission systems, due to the inherent characteristic of the distribution networks and the additional required facilities of the distance protection, compared with over-current protection, which is in use in the distribution systems. This paper studies the measured impedance at the source node of a distribution feeder with dispersed generation (DG) unit, in the case of inter, phase to phase and three phase, faults. The ideal tripping characteristic is presented for the distribution feeder with DG unit. The variation of this tripping characteristic is investigated as a function of DG unit parameters. The especial case of the absence of the fault resistance is highlighted.