The Siemens SIRIUS 3RV1321-0FC10 is a circuit breaker designed for starter combinations — meaning it integrates directly into a motor starter assembly, combining short-circuit and overload protection in one device. For a 400 V motor load, the rated power is 0.12 kW — a small motor, fractional-horsepower class. The 5.5 W power dissipation in hot operating state (1.8 W per pole) matters for enclosure heat rise; if you pack several of these in a small cabinet, add that to your thermal budget.
Mounting and integration — DIN-rail fit
The 45 mm width (3 module spaces) and 96 mm depth fit standard enclosure layouts. Zero clearance required at the back or sides, so it can butt against adjacent devices. Any mounting position is allowed — no derating for orientation. Screw-type terminals for both main and auxiliary/control circuits accept solid or stranded conductors: 2x (1 … 2.5 mm²) and 2x (2.5 … 6 mm²) per clamp. AWG equivalents are 2x (14 … 10).
RoHS compliance date is 01.05.2012, meaning it meets the EU RoHS directive from that date forward. The surge voltage resistance is rated at 6,000 V, and touch protection is finger-safe per IP20. Ground fault and phase failure detection are not built in — those functions would need an external relay or a different SIRIUS variant.