What it is and what the ratings mean
The Siemens 3VA2340-6KP32-0AG0 is a SENTRON molded case circuit breaker (MCCB) for line protection, rated at a continuous current Iu of 400 A across three poles. The ETU850 electronic trip unit handles the protection curve, so you get adjustable long-time, short-time, instantaneous, and ground-fault settings — not a fixed thermal-magnetic trip. The interrupting ratings are the headline here: 242 kA at 240 V, 187 kA at both 415 V and 440 V, 121 kA at 500 V, and 40 kA at 690 V. Those numbers mean it can safely clear a fault at those levels without welding contacts or cascading upstream — critical for high-fault-capacity panels where a standard MCCB would blow apart.
Thermal derating and real-world fit
At 40 °C, 45 °C, and 50 °C the breaker holds its full 400 A rating. At 55 °C it derates to 375 A, at 60 °C to 350 A, at 65 °C to 325 A, and at 70 °C to 300 A. That matters when you're stuffing this into a crowded enclosure where ambient climbs — the 96 W max power loss adds heat you need to vent. The 110 mm depth, 138 mm width, and 248 mm height mean it fits standard SENTRON mounting bases and busbar systems; no oddball footprint. Operating range is -25 °C to 70 °C, storage from -40 °C to 80 °C.
What's on board and what's not
Comes with a communication function (likely PROFIBUS or PROFINET via the 3VA communication module) and an 'other measurement function' — the ETU850 can report load current and trip event data. The auxiliary contact configuration is one auxiliary switch plus one trip alarm switch (HP type). No undervoltage release, no voltage trigger, no phase failure detection, no ground fault monitoring module built in. The integrated auxiliary trip is order code 3VA9608-0BB11; the supplied basic switch is 3VA2340-6KP32-0AA0. Mechanical endurance is 15,000 operations.