What this 45 A motor protection breaker is and where it fits
The Siemens 3RV1031-4GA15 is a SIRIUS motor protection circuit breaker rated for 45 A continuous current with a CLASS 10 trip characteristic, sized for 22 kW motor loads at 400 V AC. It snaps onto a 35 mm DIN rail per DIN EN 50022 and uses screw-type box terminals for the main circuit — the same footprint as the rest of the SIRIUS 3RV10 family, so it drops into existing panel layouts without re-drilling. The 45 A rating governs the motor full-load current it can carry continuously. The CLASS 10 trip means it will disconnect within 10 seconds at 600% of the set current, which is the standard for standard induction motor starting — enough to ride through a normal start but fast enough to protect against a locked rotor.
Breaking capacity and fault coordination
This breaker clears 100 kA at 240 V AC, 50 kA at 400 V AC, 10 kA at 500 V AC, and 4 kA at 690 V AC. The 50 kA at 400 V is the figure that matters for most European 400 V panels — it means the breaker can safely interrupt a bolted fault at the main distribution level without needing an upstream current-limiting fuse, as long as the available fault current at the panel doesn't exceed that. At 690 V the 4 kA rating is lower, so verify the SCCR if you're running a 690 V drive input. Phase failure detection is built in — the breaker will trip if one phase drops out, which prevents single-phasing damage to the motor. Ground fault detection is not included, so for ground-fault protection you need an external module or a separate ground-fault relay.
Mounting, wiring, and environment
Mounts in any position on 35 mm DIN rail via the integrated snap-on foot. The front face is IP20 — finger-safe from the front, but the terminals are not sealed, so keep it inside an enclosure rated for the environment. Operating temperature is -20 to +60 °C; storage and transport range is -50 to +80 °C. Main circuit terminals accept solid conductors: 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²). Stranded conductors: 2x (0.75 to 25 mm²) or 1x (0.75 to 35 mm²). AWG equivalents for the main contacts are 2x (18 to 2) or 1x (18 to 2). The auxiliary and control circuit uses separate screw terminals. Shock-rated to 25g for 11 ms — tough enough for most industrial machinery.