The power supply radius of a transformer refers to the distance from the transformer to the farthest power-consuming device. It is affected by several factors, including voltage level, cable type, load size, and voltage quality requirements. Generally speaking, the low-voltage power supply radius should not exceed 250 meters, while the high-voltage power supply radius can be increased depending on the specific situation.
The following are some factors and recommendations that influence the power supply radius:
1. Voltage Level:
Higher voltage levels generally have a larger power supply radius than lower voltage levels because higher voltage effectively reduces voltage losses along the line.
For example, the power supply radius of a 10kV line is generally larger than that of a 6kV line.
2. Cable Type and Cross-Section:
The cable material and cross-sectional area affect its current carrying capacity and voltage loss, thereby affecting the power supply radius.
Typically, copper wire has a larger power supply radius than aluminum wire because copper wire has lower resistivity.
For longer power supply radiuses, a larger cable cross-section may be required to reduce voltage losses.
3. Load Size and Distribution:
The power and distribution of the loads affect the transformer’s load factor and line voltage losses, thus affecting the power supply radius. Generally speaking, areas with concentrated and large loads have a relatively small power supply radius; areas with dispersed and smaller loads can have a larger power supply radius.
In addition, the transformer capacity should be appropriately matched to the load conditions, avoiding over- or under-sizing.
4. Voltage Quality Requirements:
For some electrical equipment with high voltage quality requirements, the power supply radius needs to be more strictly controlled to ensure voltage stability and reliability.
Technical measures such as adding compensation capacitors and adjusting transformer taps may be necessary to improve power supply quality.
5. Power Supply Mode and Wiring Method:
Adopting a “multi-point, short radius, small capacity” power supply model can effectively improve power supply reliability and power quality.
Replacing the traditional centralized power supply method with a wiring method that radiates from the power point can reduce line detours and shorten the power supply radius.
Summary:
The transformer power supply radius is a complex issue that requires comprehensive consideration of multiple factors. In actual projects, calculations and analysis are required to select the appropriate power supply radius and transformer capacity to ensure reliable, economical, and safe power supply. Some reference data:
The power supply radius of low-voltage lines for trunk lines generally does not exceed 250 meters, according to the “Technical Measures for Civil Construction Projects.”
The power supply radius of branch lines from the final distribution box to the terminals of power-consuming equipment should be controlled within 50 meters.
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.
The power supply radius of 10kV lines is less than 15km, and the power supply radius of 0.4kV lines is less than 0.5km.
Post time: Aug-04-2025
