The Schneider Electric C40H37E400 is a ComPacT NSX400H molded case circuit breaker (MCCB) with a MicroLogic 7.3 E electronic trip unit, rated 400 A at 40 °C. The MicroLogic 7.3 E trip unit provides L (long-time overload), S (short-time short-circuit), I (instantaneous short-circuit), and R (earth-leakage) protection. That R function is key — it integrates ground-fault protection into the breaker itself, saving a separate relay and CT. The electronic trip gives you adjustable curves, so you can coordinate selectively with downstream breakers without swapping trip units. It includes an LCD display for local metering — energy, demand, power quality — and logs time-stamped events. Mechanical durability is 15,000 cycles; electrical durability is 12,000 cycles at 440 V at half rated current, or 6,000 at full rated current.
Front connections both top and bottom. Connection pitch is 45 mm. Relative humidity 0–95%. The toggle control is straightforward — ON/OFF, plus a rotary switch for the earth-leakage threshold. Six accessory slots available for auxiliary contacts, shunt trips, or communication modules. IK07 impact resistance per IEC 62262 means it handles a 2 J hammer blow — fine for panel doors, not for direct abuse.