In modern power systems, the distribution segment serves as the critical bridge interconnecting bulk power grids with end-use consumers. The stability and operational efficiency of distribution systems directly determine energy utilization efficiency and electrical safety, underpinning industrial manufacturing, urban functional operations, and daily residential life alike. As a pioneering enterprise in smart grid solutions, PEOPLE has consistently propelled the evolution of distribution paradigms through technological innovation, providing robust support for the global energy transition. This article systematically categorizes and elaborates on the distinct modes of alternating current (AC) power supply deployed in distribution systems.
AC Power Supply Modes: Flexibility and Efficiency as the Backbone of Modern Power Grids
Alternating current (AC) power supply has established itself as the mainstream solution in contemporary distribution systems, thanks to its inherent advantages including facile voltage stepping-up, high long-distance transmission efficiency, and lower capital and operational costs for associated power equipment. Classified by voltage rating and wiring configuration, AC power supply systems are divided into the following standardized categories:
Three-Phase Three-Wire System
This configuration realizes high-efficiency transmission of three-phase electrical energy through delta (△) connection or star (Y) connection topologies. With a simplified structural design and stable power output characteristics, it is exclusively applicable to scenarios involving three-phase balanced loads. It is extensively deployed in high-voltage distribution networks (e.g., 35kV–60kV systems), industrial motor drive assemblies, and large-scale dedicated industrial/commercial lighting systems.
Three-Phase Four-Wire System
Composed of three phase conductors (live wires) and one neutral conductor, this system delivers a hybrid voltage supply of 380V/220V. It features exceptional operational flexibility, capable of simultaneously satisfying the power demand of high-power three-phase equipment (operating at 380V) and low-power single-phase loads (operating at 220V). This mode is universally adopted in low-voltage mixed distribution networks for motive power and lighting, with core applications spanning residential quarters, commercial complexes, urban public facilities, and general industrial workshops.
Single-Phase Two-Wire System
This basic configuration comprises only one phase conductor and one neutral conductor, providing a standardized single-phase 220V supply. It boasts low construction costs, straightforward wiring installation, and convenient operation and maintenance, yet is constrained by limited load-carrying capacity. It is predominantly utilized for powering residential indoor lighting circuits, small household appliances, and low-power single-phase office equipment.
Other Specialized Configurations
Three-Phase Two-Wire with Earth Return System: Previously implemented in rural distribution networks, this mode has been gradually phased out in modern power systems due to inherent deficiencies in electrical safety, operational reliability, and power quality.
Three-Phase Single-Wire System: A dedicated configuration exclusively designed for electric railway traction power supply, with the 27.5kV single-wire traction power supply system being the most representative application for electrified railways and high-speed rail networks.
Post time: Feb-05-2026
