What it is and where it fits
The Siemens 3RV1031-4HA10-0BA0 is a SIRIUS motor protection circuit breaker, designed for motor protection in main current circuits. It's rated for 50 A continuous and delivers 22 kW at 400 V, with a CLASS 10 trip characteristic that clears overloads fast enough to protect standard induction motors during start-up. Phase failure detection is built in, so a lost phase won't cook the winding while the breaker holds. Mounts via screw and snap-on onto 35 mm DIN rail per EN 50022, in any position. The IP20 front face keeps fingers out of live terminals inside the panel; the breaker itself is panel-internal, not for washdown zones.
Breaking capacity — what it clears
Rated breaking capacity varies with line voltage: 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. At 400 V — the most common industrial supply — that 50 kA SCCR covers nearly any distribution panel downstream of a transformer. The 690 V rating is lower but still adequate for 690 V motor circuits with limited fault current.
Terminals and wiring
Main circuit terminals are screw-type box terminals. Solid wire: 2x (0.75... 16 mm²). Stranded: 2x (0.75... 25 mm²) or 1x (0.75 … 35 mm²). Fine-stranded with ferrule: 2x (0.75... 16 mm²) or 0.75... 25 mm². AWG equivalent for main contacts: 2x (18... 2) or 1x (18... 2). That range covers everything from control-circuit tails to motor feeder cable up to 35 mm². Auxiliary and control circuits use separate screw terminals.
Physical fit and environment
Dimensions: 55 mm wide, 140 mm high, 149 mm deep. Zero clearance needed at the sides or rear — backwards 0 mm, at the side 0 mm — so it tucks tight against other devices on the rail. Operating temperature: -50 to +60 °C. Storage and transport: -50 to +80 °C. Shock rated at 25 g for 11 ms. Power dissipation at full load in hot state: 29 W total, 9.7 W per pole. That's warm but manageable in a ventilated enclosure; don't bury it next to a drive without some airflow.