SIRIUS 3RV1021-0KA10 — Motor Protection Circuit Breaker, 1.25 A, Class 10
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. Its Class 10 trip characteristic means it disconnects within 10 seconds at 7.2× the set current — fast enough to protect standard induction motors during a stall or locked-rotor event without nuisance tripping on normal start-up. Breaking capacity is 100 kA across the full voltage range (240 V through 690 V AC), so it can interrupt a bolted fault at the motor terminals without upstream fuses or a larger breaker — useful in high-fault panels where coordination is tight. Phase failure detection is built in; ground fault detection is not. For a motor branch that needs ground-fault protection, pair it with a separate ground-fault relay or choose a variant that includes it.
Mounting and Panel Integration
Mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 50022. 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. Mounting position is any, which simplifies panel layout when space is tight. Screw-type terminals on both main and auxiliary/control circuits. 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. IP20 on the front — protected against finger contact but not moisture. Suitable for dry indoor panels; not rated for washdown or outdoor installation without an additional enclosure.
Lifecycle and Sourcing
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. Ambient operating range -20 to +60 °C; storage and transport -50 to +80 °C. Shock resistance 25 g for 11 ms — robust enough for most industrial machinery but not rated for continuous vibration environments like crushers or shakers.