What this MCCB delivers
The Siemens SENTRON 3VA2340-6JP32-0KA0 is a 3-pole molded case circuit breaker (MCCB) rated for 400 A continuous current, built around the ETU550 electronic trip unit. It's a line-protection breaker — no ground-fault monitoring, no phase-failure detection, no auxiliary contacts on the base unit — but it does carry a shunt trip (STL) auxiliary release and a voltage-trigger function for remote tripping. The communication function is onboard, so it can talk to a BMS or PLC without an add-on module. Breaking capacity is substantial: 242 kA at 240 V, 187 kA at 415 V and 440 V, 121 kA at 500 V, and 40 kA at 690 V. That covers most industrial service-entrance and feeder applications where high fault current is a given. The rated insulation voltage is 800 V, so it's comfortable on 690 V systems with margin.
Thermal derating — plan your panel ambient
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. If your panel ambient runs above 50 °C, size the breaker for the derated current — not the nameplate 400 A. Maximum power loss is 96 W, so ventilation or spacing matters in a dense enclosure. Dimensions are 110 mm deep, 138 mm wide, 248 mm tall. That's a standard 3-pole MCCB footprint for this class — fits most SENTRON mounting bases and panel cutouts. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C.
What's inside — trip unit and releases
The ETU550 is an electronic trip unit with LSI protection (long-time, short-time, instantaneous). It's field-adjustable and supports communication, so you can read trip events and settings remotely. The integrated shunt trip (STL) is part number 3VA9688-0BL33 — if you need a spare release, that's the order code. The base switch without the shunt trip is 3VA2340-6JP32-0AA0.