The ABB E4S4000 PR121/P‑LSIG 4000 A 3‑pole WHR Air Circuit Breaker is a high‑capacity low‑voltage protection device from ABB’s SACE Emax E4 series designed for industrial and commercial three‑phase electrical distribution systems. It includes an electronic PR121/P‑LSIG trip unit, which provides adjustable protection for overloads, short‑time faults, instantaneous short circuits, and ground faults. The breaker has a withdrawable design (WHR) so it can be safely inserted and removed from switchgear without disconnecting the main busbars, facilitating maintenance and servicing. It is suitable for use as a main distribution breaker or feeder protection breaker in switchboards, switchgear, and power distribution panels.
