SCCR and thermal derating — what the numbers mean for your panel
The Siemens SENTRON 3VA2440-5HN32-0AJ0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, carrying 400 A continuous current (Iu) at 40 °C through 50 °C, then derating to 384 A at 55 °C, 376 A at 60 °C, 368 A at 65 °C, and 360 A at 70 °C. That means in a 50 °C panel — common for enclosed switchgear — you still get full 400 A; above that, you must downrate the load or the breaker will nuisance-trip on thermal memory. Short-circuit breaking capacity is the headline: 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. For a 480 V distribution panel in North America, the 121 kA at 440 V is the closest published point — well above typical 65 kA or 100 kA available fault current, so this breaker can be applied at the main or a high-fault subfeed without cascading upstream. Rated insulation voltage Ui is 800 V, so the breaker is suitable for 690 V line-to-line systems (common in mining, marine, and European industrial grids) with the 17 kA SCCR at that voltage. The ETU350 electronic trip unit provides adjustable long-time, short-time, instantaneous, and ground-fault protection — it's the same platform used across the 3VA2 frame, so settings are consistent with other breakers in the same family.
Panel integration and auxiliaries
Dimensions: 248 mm high, 138 mm wide, 110 mm deep. The 138 mm width is the standard 3-pole MCCB footprint for the SENTRON 3VA2 frame — fits existing cutouts and busbar risers without panel rework. IP40 on the front face means it's protected against tools and small wires, but not against water ingress; mount in a dry enclosure or add a cover for washdown areas. Auxiliary contact version is 2 auxiliary switches plus 1 trip alarm switch (HP type). That gives you two NO/NC status contacts for PLC feedback and one dedicated alarm contact that changes state only on a trip event — useful for remote fault annunciation without polling the trip unit. No undervoltage release, no shunt trip, no communication module on this variant; those are separate order-code options if needed. Maximum power loss is 63.5 W. In a sealed enclosure with multiple breakers, that heat must be factored into the thermal budget — at 400 A continuous, the breaker dissipates about 0.16 W per amp, which is typical for an electronic-trip MCCB of this frame size.