The ABB REM543 is a comprehensive and integrated protection and control device designed for demanding medium-voltage applications. It provides a versatile solution for the protection, control, measurement, and supervision of feeders, motors, and transformers in utility and industrial power systems. This compact unit combines multiple functions, including overcurrent, earth-fault, and thermal overload protection, along with advanced motor protection features like start-up supervision and locked rotor protection. The REM543 enhances system reliability and simplifies engineering by integrating extensive functionalities into a single, user-friendly device.