What this MCCB is and what it does
The Siemens 3VA2440-6HN32-0JH0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection in distribution panels. It carries a continuous current rating of 400 A across the full ambient temperature range from 40 °C to 70 °C — no derating needed up to that ceiling, which simplifies panel layout when the breaker sits near other heat sources. Three-pole construction, so it switches all three phases simultaneously. The interrupting ratings climb steeply at lower voltages: 242 kA at 240 V AC, 187 kA at 415 V and 440 V, 121 kA at 500 V, and 9 kA at 690 V. That 242 kA figure at 240 V tells you this breaker is built for high-fault-capacity service entrances or large sub-distribution boards where available fault current is substantial.
Built-in accessories and what they mean on the bench
This variant ships with a shunt trip (STL) for remote tripping, plus two auxiliary switches and one trip alarm switch (HQ configuration). The auxiliary switches let a PLC or building management system see the breaker position; the trip alarm gives a dedicated signal when the breaker has opened on a fault, not just manually. That distinction matters during fault-finding — you know immediately whether the open was commanded or protective. The base switch inside is order code 3VA2440-6HN32-0AA0, so if you ever need to replace just the switching mechanism, that's the spare part to order. No undervoltage release on this build, and no ground-fault monitoring module fitted. Power loss at full rated current is 63.5 W — plan for that heat inside the enclosure, especially if the panel is densely packed.
Physical fit and environment
Dimensions: 248 mm high, 138 mm wide, 110 mm deep. That 110 mm depth is the dimension you need to check against gland-plate clearance or a shallow backbox — it's not a slimline breaker. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. The storage range is wider because the breaker isn't dissipating heat when it's sitting on a shelf.