The Siemens 3RV6311-0DC10 is a SIRIUS circuit breaker sized for starter combinations — it's the overload and short-circuit protection block that sits ahead of a contactor in a motor starter assembly. Rated 0.32 A at AC-3 (400 V) with a 690 V insulation voltage, it's built for small motor loads or control transformers where you need coordinated protection in a compact S00 frame.
The 0.32 A operational current at AC-3 (400 V) sets the motor full-load current it can handle — pair it with a contactor rated for the same duty class. The instantaneous short-circuit trip responds at 4.2 A, so it clears a fault fast without waiting for the upstream breaker to coordinate. That magnetic trip is fixed, not adjustable, so verify your motor's inrush won't nuisance-trip it. The 5 W typical power loss is low enough that you don't need to derate adjacent components in a crowded DIN rail assembly.
The S00 footprint — 45 mm wide, 96 mm deep, 97 mm tall — fits the common narrow slot in a motor starter row. Screw-type terminals on top and bottom accept 2x (0.75…2.5 mm²) solid/stranded or 2x 4 mm². Torque to 0.8…1.2 N·m. For AWG, that's 2x (18 to 12) or 2x (20 to 16) — standard for control wiring in a panel.