What it is and what the ratings mean for fit
The Siemens 3VA2340-5JQ42-0DL0 is a SENTRON molded case circuit breaker (MCCB) with a 400 A rated continuous current, 4 poles, and an ETU560 electronic trip unit. It is a line-protection version — meaning it is set up for feeder or main breaker duty, not motor-circuit protection, so the trip curve and accessories are tuned for cable and busbar protection rather than motor starting inrush. The interrupting ratings tell you where this breaker can sit in a fault-current study: 187 kA at 240 V AC, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 17 kA at 690 V. At 400 A frame size, those numbers are high enough for most secondary main or large feeder positions without needing a current-limiting fuse upstream. The 690 V figure is the one to watch for 600 V class industrial systems — 17 kA is solid but check your available fault current before committing the BOM line. Thermal derating is published per degree: full 400 A up to 50 °C, then 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C. If the panel ambient runs above 50 °C, the breaker still carries the load but you need to account for the reduced rating in the coordination study.
Integration and panel fit
Dimensions are 248 mm high, 184 mm wide, 110 mm deep. It mounts on a DIN rail or can be screw-fixed to a backplate. The 184 mm width for a 4-pole 400 A frame is standard for this class — check your enclosure gland-plate clearance and phase-barrier spacing before laying out the panel. Auxiliary contact configuration is 2 auxiliary switches + 1 trip alarm switch + 1 electrical alarm switch HQ. That gives you status feedback for the SCADA or PLC — one set for breaker open/closed, one for trip indication, and one for electrical alarm. The undervoltage release (UVR) is factory-fitted; it drops the breaker when control voltage falls below the dropout threshold, which is typical for emergency-stop or undervoltage protection schemes. Communication function is built in — the ETU560 supports PROFIBUS or PROFINET via a communication module, letting you read current, power, energy, and trip data remotely. That is useful for a main breaker in a power-monitoring scheme, but confirm the specific module variant for your network protocol.