2CMA100155R1000 ABB B21 312-100 65 A Single-Phase Energy Meter RS-485

Why Choose the ABB B21 312-100 Energy Meter?

The ABB B21 312-100 is an advanced compact single-phase DIN-rail energy meter designed for direct-connected electrical installations up to 65 A. Part of ABB's DIN Rail Mounted Meters range, it provides accurate monitoring of active and reactive energy in residential, commercial and building energy-management applications.

Designed for 220–240 V AC single-phase systems, the B21 312-100 supports bidirectional energy measurement with separate import and export registers. Its backlit display provides clear local readings, while multiple instrumentation values, event logging, alarm functionality and support for up to four tariffs make it suitable for detailed energy monitoring and submetering applications.

Integrated RS-485 communication supports Modbus RTU and EQ Bus, enabling straightforward integration with building management and energy-monitoring systems. The meter also provides two inputs and two outputs configurable for functions including pulses and alarms, while direct measurement up to 65 A eliminates the need for external current transformers in suitable installations.

Key Advantages

• Direct-connected measurement up to 65 A without external current transformers.
• Designed for single-phase 220–240 V AC electrical systems.
• Measures both active and reactive energy.
• Separate import and export energy registers support bidirectional monitoring.
• RS-485 communication for integration with external monitoring and management systems.
• Supports Modbus RTU and ABB EQ Bus communication.
• MID Class B / IEC Class 1 active-energy accuracy.
• Supports up to four tariffs for flexible energy accounting.
• Two inputs and two outputs provide flexible pulse and alarm functionality.
• Compact two-module DIN-rail format simplifies installation in distribution boards.

Key Features

• ABB B21 series energy meter.
• Single-phase direct-connected measurement.
• Maximum direct current measurement of 65 A.
• 220–240 V AC operating voltage range.
• Active and reactive energy measurement.
• Import and export energy measurement in separate registers.
• Resettable intermediate energy register.
• Support for up to four tariffs.
• RS-485 Modbus RTU / EQ Bus communication.
• Two inputs and two outputs for pulse, alarm and related functions.
• Multiple instrumentation values for detailed electrical monitoring.
• Up to 25 possible alarms and event logging.
• Easy-to-read backlit display.
• MID approved and verified.
• IEC approved.

Advanced Energy Monitoring with RS-485 Communication

The ABB B21 312-100 combines direct-connected energy measurement with digital communication and flexible monitoring functions in a compact DIN-rail enclosure. Active and reactive energy can be recorded in separate import and export registers, while a resettable intermediate register and support for up to four tariffs provide additional flexibility for submetering, energy allocation and consumption analysis.

Its integrated RS-485 interface supports Modbus RTU and EQ Bus, allowing measurement data to be incorporated into compatible building management, automation and energy-monitoring systems without relying solely on local readings. Combined with configurable inputs and outputs, alarm functions and event logging, the B21 312-100 is well suited to installations requiring accessible and detailed electrical energy data.

Typical Applications

• Residential energy monitoring and submetering.
• Commercial building energy monitoring.
• Tenant and departmental energy metering.
• Single-phase distribution board monitoring.
• Building management systems using RS-485 communication.
• Modbus RTU energy-monitoring networks.
• Import and export energy measurement.
• Multi-tariff electricity monitoring.
• Energy efficiency and consumption analysis.
• Direct-connected circuits requiring measurement up to 65 A.