The Siemens 3RV1021-0KA10 is a SIRIUS motor protection circuit breaker rated for 1.25 A continuous current, sized for a 0.37 kW motor at 400 V AC. For a motor branch that needs ground-fault protection, pair it with a separate ground-fault relay or choose a variant that includes it.
The 45 mm width occupies a single modular unit — plan for one 45 mm slot in the enclosure layout. Depth is 96 mm, height 97 mm. Solid and stranded conductors accepted: 2× (1 … 2.5 mm²) and 2× (2.5 … 6 mm²) per terminal, or AWG 14–10 for the main contacts. Finely stranded with ferrule is also supported at the same cross-sections.
RoHS compliance date is 01.05.2012, confirming it meets the EU RoHS directive for hazardous substance restrictions. No UL or CSA listing is explicitly stated in the evidence, but the SIRIUS series typically carries IEC certification (EN 60947). Verify specific agency approvals with the order desk if your panel requires UL listing.
Electrical and Environmental Ratings
Rated insulation voltage 690 V; maximum operating voltage in AC-3 duty is also 690 V. Surge voltage withstand is 6 kV. Operating frequency at AC-3 is 15 operations per hour maximum — adequate for infrequent motor starts; not for high-cycling applications like rapid reversing. Power dissipation: 7.25 W total in hot operating state, or 2.4 W per pole. Factor this into enclosure thermal calculations — at 7.25 W, it's a modest heat source but should not be buried next to other high-dissipation devices without airflow. Shock resistance 25 g for 11 ms — robust enough for most industrial machinery but not rated for continuous vibration environments like crushers or shakers.