The ABB E4S4000 PR121/P‑LSIG 4‑pole WHR Air Circuit Breaker is a high‑capacity low‑voltage protection device from ABB’s SACE Emax E4S series designed for three‑phase industrial and commercial electrical distribution systems. It features a PR121/P‑LSIG electronic trip unit, which provides advanced adjustable protection against overloads, short circuits, instantaneous faults, and ground fault conditions. The breaker’s withdrawable (WHR) design allows safe extraction and servicing within a switchgear frame without disconnecting the main busbar connections. This unit is suitable for use as a main distribution feeder breaker, critical load protection, or industrial power system breaker where high reliability and protection performance are required.
