The REM 54_ rotating machine terminals (hereafter referred to as “machine terminals”) are designed to serve as the primary protection system for generators and generator-transformer units in small and medium-power diesel, hydroelectric, and steam power plants. Another key application area is the protection of large and/or critical medium-voltage synchronous and asynchronous motors—such as those driving pumps, mills, and crushers—during both start-up and normal operation.

The range of available functions depends on the selected functionality level (refer to Ordering Information on page 91) and is also influenced by the installed hardware configuration. Within the limits of I/O availability and total CPU load, users can activate the required functions from a wide set of protection, control, measurement, condition-monitoring, general, and communication features. Compared to traditional setups that use several separate devices, the ability to combine multiple functions in one unit provides a cost-effective solution. Relay configuration according to IEC 61131-3 further allows the machine terminals to be easily adapted to a wide variety of applications.

The graphic HMI enables local indication of disconnector and circuit-breaker status. Additionally, the machine terminal can transmit the status of breakers and disconnectors to a remote control system. Controllable devices such as circuit breakers can be operated (opened or closed) from the remote control system, with signals and status information transmitted over the serial communication bus. Local operation via front-panel pushbuttons is also supported.

The protection functions of the machine terminals are designed to provide selective short-circuit and earth-fault protection for rotating machines. Unlike most other power system equipment, rotating machines also require protection against abnormal operating conditions. The device therefore includes functions such as overcurrent, unbalanced-load protection, overtemperature, over-/undervoltage, over-/underexcitation, over-/underfrequency, and generator motoring protection. An underimpedance function is supplied for line backup. For motor applications, stall protection and a cumulative start-up counter provide enhanced supervision during starting sequences.

The machine terminals measure phase currents, phase-to-phase or phase-to-earth voltages, neutral current, residual voltage, frequency, and power factor. From these measurements, the device calculates active and reactive power, and energy can be derived from the calculated power. All measured values can be displayed locally or transmitted as scaled primary quantities to remote systems.

In addition to protection, measurement, control, condition-monitoring, and general functions, the machine terminals incorporate a comprehensive set of PLC functions. These allow various automation and sequence-logic tasks required for substation automation to be integrated within a single unit. Communication capabilities include SPA bus, Modbus, and LON bus protocols for interfacing with higher-level systems. LON communication, when combined with the built-in PLC functionality, significantly reduces the amount of hardwiring needed between machine terminals.

ABB REM543BM215AAAB｜Circuit Breaker Control Module｜