Rail-mounted watt-hour meter is a high-precision electric energy metering equipment using international standard DIN rail (width 35 mm) installation method, it is mainly used to monitor the electrical parameters such as power consumption, voltage, current and power of single-phase or three-phase circuits. It has the characteristics of small size, convenient installation and accurate data, it is widely used in household metering, commercial store power distribution, industrial equipment energy consumption monitoring and other scenarios, and is the core component to realize the fine management of electric energy.