The ABB E4S4000R4000 PR121/LSIG 3‑pole WMP Air Circuit Breaker is a high‑capacity low‑voltage protective device from ABB’s SACE Emax E4S series designed for three‑phase industrial and commercial power distribution systems. It incorporates an electronic PR121/LSIG trip unit which provides adjustable protection for overloads, short circuits, and instantaneous faults. The unit is configured in a withdrawable (WMP) format, allowing the breaker to be easily inserted or removed from switchgear for maintenance without disturbing the main busbar connections. This breaker is suitable as a main distribution or feeder protection device in switchboards and electrical distribution installations where high reliability and fault clearing performance are required.
