The Siemens SENTRON 3VA1140-3ED16-0AA0 is a 1-pole molded case circuit breaker (MCCB) rated for 40 A continuous current at 45 °C ambient, with a TM210 thermal-magnetic release set for line protection. At 415 V it still clears 7.5 kA, so it covers the common European 400 V line-to-line tap as well. The TM210 release gives you fixed instantaneous pickup at 400 A (10× Iu) and a thermal curve that tracks the cable's heating characteristic. No adjustable magnetic — set it and forget it for straightforward branch protection. The 70 mm depth and 25.4 mm width (one inch) mean it fits standard 25 mm DIN-rail spacing; you can pack multiple poles side by side without losing panel density.
At 55 °C it derates to 39 A, at 65 °C to 38 A, and at 70 °C to 37 A. The maximum power loss is 3.6 W, so heat buildup in a dense row is manageable, but stacking several units without ventilation gaps will raise the local temperature.