Available. The ABB REF541CM115AAAA is a multifunctional protection relay designed for medium-voltage power distribution systems. It offers comprehensive protection, control, measurement, and monitoring capabilities, ensuring the reliable operation of overhead lines, cables, and distribution networks in industrial and utility applications. This relay supports radial, ring, and mesh network configurations, making it suitable for modern smart grid requirements. Key features include multi-function protection supporting overcurrent, earth fault, and differential protection; arc fault detection to prevent electrical fires; fault location algorithms to reduce downtime; flexible communication with IEC 61850 compliance and support for multiple protocols; high isolation and surge protection for reliability and safety; and a user-friendly graphical interface for real-time monitoring and parameter adjustment. The REF541CM115AAAA operates within a wide temperature range of -20°C to +70°C, suitable for outdoor and harsh industrial settings. It is configurable via ABB’s Relion Configuration Tool for protection settings, logic programming, and diagnostics.