The Schneider Electric ENW21435 is a microprocessor-based trip unit for the EasyPact NW range of air circuit breakers. It carries a Trip System 5.0A with LSI protection — long-time, short-time, and instantaneous — covering overload, short-circuit, and earth fault. Rated operational voltage is 690 V AC (50/60 Hz) per IEC 60947-2, with a trip unit rating adjustable from 800 to 4000 A.
What the LSI protection settings mean for coordination
LSI gives you three independent protection curves: long-time (Ir) adjustable 0.4–1 x In with nine delay settings from 0.5 to 24 s at 6 x Ir; short-time (Isd) adjustable 1.5–10 x Ir with five delay settings from 100 to 400 ms; and instantaneous (Ii) adjustable 2–15 x In with nine settings or can be switched Off. That range lets you coordinate downstream with molded-case breakers or motor starters while keeping the main breaker selective upstream.
Integration into the breaker
The ENW21435 is a drawout-style control unit — it plugs into the EasyPact NW cradle without removing the breaker from the switchgear. Neutral position is left-side; neutral protection is configurable as 3D (no protection), 3D + N/2 (half-rated), or 4D (full). Protected poles can be set to 4D, 3D + N/2, or 3D. Zone selective interlocking (ZSI) is built in, which speeds fault clearing by communicating with upstream and downstream breakers — useful in large distribution boards where you want arc-flash energy kept low.