The Siemens SIRIUS 3RV1021-0KA10-0FJ0-ZX95 is a motor protection circuit breaker rated for a continuous current of 1.25 A, designed to protect a 0.37 kW motor at 400 V AC. Screw-type terminals on the main circuit accept solid or stranded conductors from 1 to 6 mm² (or 14 to 10 AWG), and the IP20 front protection keeps live parts behind the enclosure door. No backwards or side clearance is needed, so it packs tight against adjacent devices.
The 100 kA breaking capacity holds across 240 V, 400 V, 500 V, and 690 V AC — that is a flat SCCR curve, not a derated one. For a 1.25 A device this is high headroom; it means the breaker will hold its rating even on a high-fault panel bus. The maximum switching frequency of 15 operations per hour in AC-3 duty limits how often you can cycle a motor start — fine for a conveyor or compressor, not for a rapid-reversing application. Ground fault detection is not included — that would require an external module or a different variant. The auxiliary switch is present (yes), but the base unit carries zero built-in auxiliary contacts; the switch is a separate add-on that mounts to the side. Shock rated at 25 g for 11 ms, surge voltage withstand at 6 kV. Mount it in any position, up to 2 000 m altitude without derating. The 7.25 W power loss in hot operating state (2.4 W per pole) is the heat you need to vent inside the enclosure.