The Siemens 3RV6311-4AC10 is a SIRIUS circuit breaker sized for starter combinations, rated 16 A at AC-3 / 400 V and 690 V insulation voltage. The 45 mm width and 96 mm depth fit standard S00 panel footprints.
The magnetic short-circuit trip responds at 208 A, so it clears a fault fast enough to protect downstream contactors and cables without nuisance tripping on normal inrush. That's tight enough for dense DIN-rail layouts but the top/bottom gap matters for arc-chamber venting — don't pack solid against the gland plate. Terminals accept 2x (0.75 to 2.5 mm²) solid or stranded, or 2x 4 mm², with a tightening torque of 0.8 to 1.2 N·m. The screw-type connection is standard for main current circuits; no special crimp tool needed.
RoHS compliance date is 05/01/2012, so it meets the EU restriction on hazardous substances. The part carries a 6 kV surge voltage resistance and is rated for installation altitudes up to 2 000 m. Shock resistance per IEC 60068-2-27 is 25 g / 11 ms.