What it is and what it does
The Siemens SIRIUS 3RV1021-1GA10-ZW97 is a motor protection circuit breaker designed for protecting three-phase motors against overload and short circuit. It's rated for a continuous current of 6.3 A and switches motor loads up to 2.2 kW at 400 V AC (AC-3 duty). The CLASS 10 trip class means it will trip within 10 seconds at 7.2× the set current, which is fast enough to protect standard induction motors during a locked-rotor event without nuisance tripping on normal startup inrush.
Breaking capacity — what it handles in a fault
This breaker carries a breaking capacity of 100 kA at 240 V, 400 V, and 500 V AC, dropping to 6 kA at 690 V AC. That 100 kA figure at 400 V means it can safely interrupt a fault current up to 100,000 amps without welding contacts or rupturing the case — important when the breaker sits downstream of a transformer or in a high-fault-capacity distribution panel. At 690 V, the 6 kA rating still covers most motor branch circuits in industrial environments.
Mounting and wiring
Mounts via screw or snap-on onto a 35 mm DIN rail per DIN EN 50022. The 45 mm width (3 module spaces) fits standard enclosure rail. Screw-type terminals on the main circuit accept solid or stranded conductors: 2× (1 … 2.5 mm²) or 2× (2.5 … 6 mm²), with AWG equivalents of 2× (14 … 10). No special tools beyond a screwdriver needed for termination. Zero clearance required at the sides or rear — 0 mm backwards and at the side — so you can pack modules tight on the rail.
Environmental and mechanical ratings
Rated for operation from -20 °C to +60 °C, with storage and transport range of -50 °C to +80 °C. IP20 protection on the front (finger-safe terminals), suitable for installation inside a locked or tool-accessible enclosure. Shock resistance of 25g for 11 ms — survives typical industrial vibration and occasional impacts. Mountable in any position, which simplifies panel layout.
Protection and diagnostics features
Includes phase failure detection — if one phase drops out, the breaker trips to prevent single-phasing motor damage. No ground fault detection built in (you'd need a separate GFPE module for that). An auxiliary switch is available (order separately) for remote status indication. The breaker has a typical mechanical life of 100,000 operations on the main contacts, and at AC-3 duty it's rated for 15 switching operations per hour maximum — adequate for most motor start applications, but not for frequent jogging or reversing cycles.