The ABB E2N1600 DR PR121/P-LSI WMP 3P NST is a three-phase protection relay or circuit breaker designed for medium-voltage applications. It offers comprehensive protection against overcurrent, short circuits, earth faults, and leakage currents in industrial, commercial, and power distribution systems. The PR121/P-LSI relay provides Long-time, Short-time, and Instantaneous (LSI) protection, which ensures adaptable and reliable protection for a wide range of fault conditions.