What this MCCB is and what it protects
The Siemens 3VA2440-5HN32-0KC0 is a SENTRON molded case circuit breaker (MCCB) configured for line protection — meaning it guards feeders and distribution buses against overload and short-circuit, not a specific motor or load. Three poles, rated continuous current Iu of 400 A, with an ETU350 electronic trip unit that gives adjustable long-time, short-time, instantaneous, and ground-fault (if equipped) protection curves. The 800 V rated insulation voltage (Ui) tells you it's comfortable on 480 V and 600 V class systems with margin. Breaking capacity is the headline here: 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 17 kA at 690 V. That 187 kA figure at 240 V is high — this breaker handles faults on large transformer secondaries or high-capacity busways without needing a current-limiting upstream device. The 121 kA at 415 V covers most European industrial distribution panels. At 690 V the 17 kA still clears a substantial fault, but verify it against your available fault current if you're on a 690 V system.
Thermal performance and derating
Rated 400 A continuous from 40 °C through 50 °C ambient. At 55 °C it derates to 384 A, at 60 °C to 376 A, at 65 °C to 368 A, and at 70 °C to 360 A. If your panel internal ambient runs above 50 °C — common in compact, high-density enclosures — you lose about 4 A per 5 °C rise. The maximum power loss is 63.5 W, which matters for enclosure thermal calculations when grouping several breakers. Dimensions: 248 mm high, 138 mm wide, 110 mm deep. That 138 mm width for a 3-pole 400 A frame is standard for SENTRON 3VA2 — it fits the same mounting footprint as other breakers in the series, so panel cutouts and busbar layouts transfer. Operating temperature range -25 °C to +70 °C; storage range -40 °C to +80 °C.
Auxiliaries and release configuration
This variant ships with a shunt trip (STL) release — designated by the order code suffix — so it can be remotely tripped via a control signal. Two HQ auxiliary switches are fitted (form C, high-qualified for signal reliability). The basic switch assembly is order code 3VA2440-5HN32-0AA0; the integrated auxiliary trip module is 3VA9688-0BL33. No undervoltage release, no communication module, no ground-fault monitoring on this version. Mechanical endurance is rated at 15,000 operations — typical for a 400 A frame in distribution duty where it cycles infrequently (a few times per year for maintenance isolation). No voltage trip indicator on this variant.