The B21-313 energy meter is a direct connect meter designed for single-phase systems with a maximum current of 65A and voltage rating of 230 VAC. It features 2 output and 2 input ports, as well as M-Bus TP communication capability. This energy meter offers high accuracy measurements, with active energy accuracy rated at class 1% and reactive energy accuracy at class 2%. The range of measurement for the N-L voltage is between 220 V to 240 V. With an IP20 protection degree, this energy meter provides reliable protection against solid objects. It also features a backlit pixel-oriented LCD display for easy reading in various lighting conditions. In terms of functionality, the B21-313 falls under the Silver sub-group. It supports measurements of active, reactive, and apparent energy, as well as import/export of energy. The meter also has resettable energy registers and can be configured to operate in either Class 0.5 or Class 1 mode. Tariffs can be set for billing purposes, and fixed I/O connections are available. Additional features include active energy monitoring and a pulse output/alarm system. The B21-313 is designed to be mounted on a DIN rail and occupies two modules of space. Overall, the B21-313 energy meter is a versatile and accurate solution for monitoring energy consumption in single-phase systems. Its advanced functionality and user-friendly design make it suitable for various applications.