What this MCCB carries — and what it means for your panel
The Siemens SENTRON 3VA2340-5HN32-0BL0 is a 3-pole molded case circuit breaker rated for 400 A continuous current at 40 °C, with an ETU350 electronic trip unit configured for line protection. The interrupting ratings are the headline: 187 kA at 240 V, 121 kA at 415 V and at 440 V, 75.6 kA at 500 V, and 17 kA at 690 V. That 187 kA figure at 240 V means this breaker can safely clear a fault up to that level without upstream devices needing to coordinate — it is sized for high-available-fault-current main or feeder positions in a distribution panel. The thermal derating curve is published: 400 A holds flat from 40 °C through 50 °C, then drops to 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. If your panel ambient runs above 50 °C, size the breaker for the derated value, not the nameplate 400 A. The maximum power loss of 98.5 W at rated current matters for enclosure thermal calculations — that heat must be removed to stay within the operating range of -25 °C to 70 °C. The auxiliary contact configuration includes 2 auxiliary switches plus 1 trip alarm switch plus 1 electrical alarm switch HQ. That is enough for remote status indication — open/closed, trip, and an alarm — without needing an external interface module. An undervoltage release (UVR) is integrated, which drops the breaker on loss of control voltage. The basic switch element is order code 3VA2340-5HN32-0AA0, and the integrated auxiliary trip is 3VA9608-0BB11 — both serviceable spares.