What it is and what it does
The Siemens SIRIUS 3RV2031-4SA15-0BA0 is a motor protection circuit breaker designed for motor protection, with phase failure detection built in. It carries a CLASS 10 trip characteristic, meaning it will trip within 10 seconds at 7.2× the thermal setting — fast enough to protect standard induction motors during a locked-rotor event without nuisance tripping on normal starts. At 230 V it's rated for 3 kW motor loads, and the breaking capacity at 400 V AC is 25 kA, which covers the vast majority of industrial distribution panels.
Mounting and panel fit
Mounts via screw and snap-on onto 35 mm DIN rail per DIN EN 60715 — the standard for European-style panels. Any mounting position is allowed. Dimensions are 55 mm wide, 140 mm high, 149 mm deep. The 55 mm width is three 18 mm module spaces, so it occupies three slots on a DIN rail. Clearance requirements: 50 mm above and below, 10 mm at the sides for heat dissipation and arc chute venting. Main circuit terminals accept screw-type connections, with M6 bolts for the main contacts.
Breaking capacity and selectivity
Breaking capacity varies by voltage: 25 kA at 240 V and 400 V, 6 kA at 500 V, 3 kA at 690 V. For AC circuits, the figures are higher: 50 kA at 240 V and 400 V AC, 12 kA at 500 V AC, 5 kA at 690 V AC. These numbers tell you where this breaker can sit in a distribution hierarchy — at 400 V it has headroom for most sub-distribution boards, but at 690 V the 3 kA rating means it needs upstream current-limiting protection if the prospective fault current exceeds that. The 50 kA AC rating at 400 V is typical for a motor branch circuit fed from a transformer with moderate impedance.
Environmental and storage specs
Operating temperature range is -50 to +60 °C; storage and transport range is -50 to +80 °C. That's a wide thermal window — it can sit in an unheated warehouse or a hot panel near a furnace. The -50 °C lower limit is unusual for a circuit breaker; most stop at -25 °C, so this one handles cold environments like refrigerated warehouses or outdoor enclosures in northern climates.