ABB REM54 53 Machine Terminals

ABB REM_Machine Terminals Application:

The REM 54_ rotating machine terminals (referred to as "machine terminals" further on) are designed to be used as the main protection system of generator and generator-transformer units in small and medium-power diesel, hydroelectric, and steam power plants, etc. The protection of large and/or important MV synchronous and asynchronous motors used, e.g., in pumps, mills, and crushers during start-up and normal run forms another application area.

The functionality available for the machine terminals depends on the selected functionality level (refer to section "Ordering Information" on page 91) and is also tied to the hardware configuration. The desired functions can be activated from a wide range of protection, control, measurement, condition monitoring, general, and communication functions within the scope of I/O connections, considering the total CPU load. Compared to the traditional use of separate products, the combination of desired functions provides cost-effective solutions and, together with the relay configuration (IEC 61131-3 standard), allows the machine terminals to be easily adapted to different kinds of applications.

By means of the graphic HMI display, the control functions in the machine terminal indicate the status of disconnectors or circuit breakers locally. Further, the machine terminal allows status information from the circuit breakers and the disconnectors to be transmitted to the remote control system. Controllable objects, such as CBs, can be opened and closed over the remote control system. Status information and control signals are transmitted over the serial bus. Local control is also possible via the pushbuttons on the front panel of the machine terminal.

The protection functions of the machine terminals are designed for selective short-circuit and earth-fault protection of rotating machines. Further, unlike most other power system components, rotating machines also need protection against abnormal operating conditions such as overcurrent, unbalanced load, overtemperature, over- and undervoltage, over- and underexcitation, over- and underfrequency, and generator motoring. Also, the underimpedance function is provided for line backup. Furthermore, stall protection and a cumulative start-up counter are provided for motor protection and start-up supervision.

The machine terminals measure phase currents, phase-to-phase or phase-to-earth voltages, neutral current, residual voltage, frequency, and power factors. Active and reactive power are calculated from measured currents and voltages. Energy can be calculated on the basis of the measured power. The measured values can be indicated locally and remotely as scaled primary values.

In addition to protection, measurement, control, condition monitoring, and general functions, the machine terminals are provided with a large number of PLC functions, allowing several automation and sequence logic functions needed for substation automation to be integrated into one unit. The data communication properties include SPA bus, Modbus, or LONbus communication with higher-level equipment. Further, LON communication, together with PLC functions, minimizes the need for hardwiring between the machine terminals.