The ABB E3N 2500 PR121/P‑LI 3‑pole air circuit breaker is a high‑capacity low‑voltage protective device from ABB’s SACE Emax / E3N series designed for industrial and commercial power distribution systems. It provides reliable protection of three‑phase electrical circuits against overcurrent, short circuits, and electrical faults. This breaker includes an electronic PR121/P‑LI overcurrent trip unit, auxiliary contacts for status signaling, and is offered in a withdrawable (W MP) configuration for ease of maintenance and serviceability within switchgear. This model is suitable as a main distribution or feeder protection breaker in power systems with high current demands.