400 A MCCB with 187 kA at 240 V — what the ratings mean for your panel
The Siemens SENTRON 3VA2340-5HL32-0JA0 is a 3-pole molded case circuit breaker rated for 400 A continuous current at 40 °C, with a maximum breaking capacity of 187 kA at 240 V AC — that's the interrupting rating you'd need at the main service entrance of a large industrial facility where fault current is highest. At 415 V and 440 V it still holds 121 kA, dropping to 75.6 kA at 500 V and 7.5 kA at 690 V, so the SCCR headroom shrinks fast above 500 V; coordination studies should use the voltage-specific value, not the 240 V headline. Rated for line protection — meaning it's designed to protect cables and busbars against overload and short-circuit, not motor or generator circuits. The built-in shunt trip release allows remote tripping via a control signal, useful for emergency-stop or load-shedding schemes. No undervoltage release, no ground-fault monitoring, no auxiliary switch on this variant — those are separate order-code options if your BOM needs them. Dimensions: 248 mm high, 138 mm wide, 110 mm deep. The 138 mm width is a three-pole MCCB footprint — standard for a 400 A frame in a distribution panel. Mounting is bolt-on, not DIN-rail; plan for gland-plate clearance and bus-bar takeoff on the line side.
Thermal derating — the real current you can carry above 40 °C
The breaker holds 400 A continuous from 40 °C up to 50 °C without derating. At 55 °C it drops to 385 A, at 60 °C to 370 A, at 65 °C to 355 A, and at 70 °C to 340 A. If your panel ambient runs hot — say a non-climate-controlled enclosure near a furnace line — use the 70 °C figure (340 A) for your load calcs, not the nameplate 400 A. Max power loss is 96 W at rated load; that heat has to leave the enclosure. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. The storage limit governs handling and warehousing, not running — it's fine to store in an unheated warehouse in winter.