Abstract:Although the distribution network planning and design guidelines put forward the principle requirements for the power supply distance of the medium and low voltage distribution lines, there are often breakthroughs in practice whentaking into account the actual situation and technical and economic rationality. With the constraint condition of allowing voltage drop,this article calculates the maximum power supply distance of the typical wire type medium and low voltage distribution lines at different load levels, using improved loss coefficient method. Furthermore, the paper also discusses the maximum power supply distance under the economic current load level, as well as the influence of the power factor and the head-end operating voltage on the maximum power supply distance. It provides a decision-making reference for distribution network planning and construction.