400 A MCCB with ETU550 — interrupting curve and thermal derating
The Siemens SENTRON 3VA2340-5JP32-0DF0 is a 3-pole molded case circuit breaker rated for continuous current of 400 A at 40 °C through 50 °C. Above 55 °C the rating steps down: 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C — so if the panel ambient runs above 50 °C, size for the derated value, not the nameplate. The ETU550 electronic trip unit gives adjustable long-time delay (tr 0.5–17 s) and short-time delay (tsd 0.05–0.5 s), letting you coordinate selectively with downstream breakers. Interrupting capacity varies sharply with line voltage: 187 kA at 240 V, 121 kA at 415 V, 55 kA at 440 V, 36 kA at 500 V, and 7.5 kA at 690 V. At 415 V it handles 121 kA — that covers most industrial secondary-distribution fault levels.
Panel fit and enclosure sealing
Footprint is 138 mm wide (5.4 in), 248 mm tall (9.8 in), 110 mm deep — a standard 3-pole MCCB envelope.