The ABB REM545BM223AAA B is a numerical machine terminal from the REM 545 series, designed for protection, control, and monitoring of electrical power systems. Although originally conceived for generator-transformer units, this specific model is also widely applied as a feeder terminal in medium and high voltage distribution networks, thanks to its flexible I/O configuration and comprehensive protection library. The "B" revision indicates enhanced performance and updated features.
The REM545BM223AAA B offers an extensive range of protection functions suitable for feeders, generators, and transformers. Key elements include:
Overcurrent (50/51): Three-phase and earth fault with directional options (67/67N).
Differential protection (87): For transformers or generators (high-impedance or biased).
Voltage protection: Undervoltage (27), overvoltage (59), residual overvoltage (59N).
Frequency protection: Under/overfrequency (81U/O) and rate of change of frequency (81R).
Thermal overload: For cables, transformers, or motors.
Autoreclosing (79): Multi-shot with dead time and reclaim time settings.
All protection stages are independently configurable with definite time or inverse time characteristics (IEC, IEEE, or user-defined curves).

The terminal includes a powerful programmable logic controller (PLC) for custom interlocking, automation, and intertripping schemes. It can control circuit breakers, disconnectors, and tap changers via its binary outputs. The integrated disturbance recorder captures up to 120 seconds of fault data with high sampling rates, enabling detailed post-fault analysis. Measured values (I, U, P, Q, f, cosφ) are displayed locally and transmitted via communication links. The unit also features breaker condition monitoring, trip circuit supervision, and event logging.
The REM545BM223AAA B supports multiple communication protocols for seamless integration into substation automation systems. Standard rear communication ports provide options for IEC 61850, IEC 60870-5-103, Modbus RTU, and DNP3.0. Redundant Ethernet options are available for high availability. Time synchronization via IRIG-B or SNTP ensures accurate event time-stamping. The front panel includes an HMI with graphical LCD and keypad for local operation and configuration.
Measuring inputs: 4 current inputs (1/5 A) and 4 voltage inputs (100-230 V AC).
Binary I/O: Up to 24 binary inputs and 16 output relays, depending on configuration.
Power supply: 80-265 V DC or 100-240 V AC.
Case: 6U high, 19" rack or flush mount, IP54 front.
Operating temperature: -10°C to +55°C.
The REM545BM223AAA B is used in utility substations, industrial power distribution, and power plants. It is particularly suited for applications where both feeder protection and generator/transformer protection are needed within a single device platform. Its modular hardware and flexible software allow it to adapt to various roles, from simple overcurrent protection on distribution feeders to complex differential protection on step-up transformers.
With its robust design, advanced protection algorithms, and comprehensive communication capabilities, the ABB REM545BM223AAA B ensures reliable operation and helps minimize downtime in critical power system applications.



