The REM 543 machine terminals are used as the main protection system of generator and generator-transformer units in small and medium-power diesel, hydroelectric and steam power plants. The protection for 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 REM 543 machine terminals depends on the selected functionality level 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.
The protection functions of REM 543 are designed for selective short-circuit and earth-fault protection of rotating machines. Unlike most other power system components, rotating machines also need protection against abnormal operating conditions such as overcurrent, unbalanced load, overtemperature, overvoltage, over- and under-excitation, under-impedance, over- and underfrequency and generator motoring. Furthermore, stall protection and cumulative start-up counter are provided for motor protection start-up supervision.
The REM 543 terminal measures phase currents, phase-to-phase or phase-to-earth voltages, neutral current, residual voltage, frequency and power factors. Active and reactive power is 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 amount 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 or LON bus communication with higher-level equipment.