The power supply radius refers to the distance of the power line from the power source point to the farthest load point it supplies. The power supply radius refers to the physical distance of the power supply line, not the spatial distance. The low-voltage power supply radius refers to the distance of the line from the distribution transformer to the distant load point, rather than the spatial distance. The power supply radius of medium voltage lines in urban areas should not exceed 3 kilometers, and in suburban areas should not exceed 6 kilometers. When the power grid conditions cannot meet the requirements of the power supply radius, technical measures should be taken to ensure the quality of the client voltage. The power supply radius of a 0.4 kV line should not exceed 300 meters in urban areas. The distance in suburban areas should not exceed 500 meters. The length of the connecting line should not exceed 20 meters. If it cannot meet this requirement, technical measures should be taken to ensure the quality of the client’s voltage. The power supply radius is an important parameter for the location and quantity of electrical shafts. 250 meters is the power supply radius for low voltage. Considering an indoor distribution line of 50 meters, 200 meters is taken as the power supply radius for low voltage. When it exceeds 250 meters, an additional level of cable is added every 100 meters.
The low voltage distribution radius of about 200 meters refers to the power supply radius of the substation (with a secondary voltage of 380 volts). A vertical shaft is generally set up in the building with an area of about 800 square meters, and the distribution radius of the end box is generally 30-50 meters.
The power supply radius depends on the influence of the following two factors:
1. Voltage level (the higher the voltage level, the larger the power supply radius) Power supply radius
- In the transmission of the same voltage level, if the voltage drop is small, the power supply radius will be larger due to the higher the density of user terminals (i.e., the smaller the power load, the smaller the power supply radius). Comparatively speaking, under the same energy load, the power supply radius of 10kV is larger than that of 6kV. At * voltage level, the power supply radius in urban or industrial areas is smaller than that in suburban areas. When using three-phase power supply, the calculation formula for the reasonable power supply radius of copper and aluminum wires (J is the economic current density) is Lst=1.79 × 85 × 11.65/j=1773/jmLsl=1.79 × 50 × 11.65/j=1042/jm. When using single-phase power supply, the calculation formula for the reasonable power supply radius of copper and aluminum wires is as follows. Ldt=4.55 × 14 × 13.91/j=885/jm (11) Ldl=4.55 × 8.3 × 13.91/j=525/jm (12) After selecting the economic section, its * reasonable power supply radius is greater than 0.5km for all three phases and three to four hundred meters for a single phase. Therefore, simply specifying no more than 0.5km is “excessive energy” for three phases and “insufficient energy” for a single phase.