Rural electrification in ethiopia with the Shield Wire Scheme

Firstly, the paper briefly describes the technique for 3-phase and single-phase power distribution along HV (115–330kV) transmission lines via the insulated shield wires, energized at MV (20–34.5kV) from the main HV/MV transformer stations, using the ground as a MV phase conductor. A computer program based on phase coordinates is presented, expressly developed for the analysis of this unconventional low cost grid based rural electrification technique, referred to as the “Shield Wire Scheme” (SWS). The paper then describes the SWSs in operation or under construction in Ethiopia. The design criteria and the commissioning results are reported for three “Single-Phase Earth-Return” SWSs, which have been put into operation in 2003. The planning and engineering criteria applied for four “3-Phase” SWSs under construction at the time of writing are then described. These SWSs will provide electricity to 50 villages and small town, to irrigation pumping stations, to two large state owned farms, and to tea, coffee and fruit processing plants employing 7000 workers. Brief information is given on SWSs in operation, under construction and planned in other developing countries.