The ABB PR121/P‑LSIG is an electronic overcurrent protection trip unit designed to be installed in compatible ABB low‑voltage air circuit breakers (ACBs). It provides adjustable and coordinated protection for three‑phase electrical distribution systems by detecting and responding to abnormal current conditions. The unit integrates multiple protection functions for comprehensive fault detection and system safety, including overload, short‑time currents, instantaneous short circuits, and ground faults. The PR121/P‑LSIG is suitable for industrial, commercial, and utility applications where reliable current protection, flexible coordination, and status indication are required.
