The ABB PR122/P‑LSI is an electronic overcurrent protection trip unit designed for use in ABB’s low‑voltage air circuit breakers (ACBs). It provides adjustable and coordinated protection for three‑phase power distribution systems by detecting and interrupting abnormal current conditions. The PR122/P‑LSI unit integrates long‑time (L), short‑time (S), instantaneous (I), and ground fault (G) protection functions, enabling flexible setting ranges for system coordination and selective fault clearing. It is suitable for industrial, commercial, and utility electrical installations where reliable protection and tuning are required. The “3P” designation indicates protection in three polar phases (typically three‑phase systems).
