What the ratings mean for fit
The Siemens SENTRON 3VA2340-5JQ32-0AH0 is a 3-pole molded case circuit breaker rated for line protection, carrying a continuous current of 400 A at ambient temperatures up to 50 °C without derating. Above that, the thermal curve steps down: 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C — so a panel running at 60 °C ambient loses 50 A of headroom. The interrupting capacity is the headline: 187 kA at 240 V, 121 kA at both 415 V and 440 V, 75.6 kA at 500 V, and 7.5 kA at 690 V. That 187 kA at 240 V means it can clear a fault at the full available short-circuit current of a large transformer-fed distribution board without cascading upstream. The adjustable trip range spans 600 A minimum to 4 000 A maximum, with an initial value of 80 A and full-scale of 400 A — the electronic trip unit is field-configurable for coordination studies.
Panel integration and mounting
The breaker measures 248 mm high, 138 mm wide, and 110 mm deep — a standard MCCB footprint for a 400 A frame. It mounts on a DIN rail or directly to a backplate; the 138 mm width fits a 3-pole unit in a typical distribution panel without crowding adjacent feeders. The auxiliary switch configuration includes 2 auxiliary switches plus 1 trip alarm switch (HQ design), which can be wired into a PLC or annunciator for remote status. No undervoltage release or other auxiliary release is fitted on this variant, so if undervoltage protection is needed, specify the release separately. Power loss is 96 W maximum at rated current — factor that into enclosure ventilation calculations.