What this part is and what it does
The Siemens SIRIUS 3RV2031-4PB10-0BA0 is a motor protection circuit breaker in the S2 frame size, designed to protect induction motors against overload, short-circuit, and phase failure. Trip Class 20 means it allows a 20-second hot-start locked-rotor time before tripping — standard for most general-purpose motor starters where the load has moderate inertia, like pumps, fans, and compressors. Phase failure detection is built in, so a lost phase on the line side trips the breaker before single-phasing damages the motor winding. Rated operating voltage spans 20 to 690 V, with breaking capacities that scale with voltage: 50 kA at 240 V, 30 kA at 400 V, 5 kA at 500 V, and 2 kA at 690 V. Under AC conditions, the same breaker delivers 50 kA at 240 V AC, 50 kA at 400 V AC, 10 kA at 500 V AC, and 4 kA at 690 V AC. That 50 kA at 400 V AC is the figure that matters for most industrial panels in 400 V distribution — it safely interrupts a fault up to that level without cascading upstream, assuming the supply transformer can deliver that fault current.
Mounting and integration
Mounts via screw fixing or snap-on onto 35 mm standard mounting rail per DIN EN 60715 — the universal DIN rail found in every control cabinet. Any mounting position is allowed, so it fits tight enclosures where rail orientation varies. Clearance requirements: 50 mm above and below the breaker for arc venting, and only 10 mm at the sides. That 10 mm side clearance is tight enough to pack breakers side-by-side in a multi-motor starter panel without wasting rail space. Main circuit terminals are screw-type, accepting 2x 1...25 mm² or 1x 1...35 mm² solid or stranded copper. The screwdriver shaft diameter is 5 to 6 mm, Pozidriv size 2 tip. Main contact terminal screws are M6. Wire the line side through the top terminals, load side out the bottom — standard top-feed practice for motor protection breakers used with contactors downstream.
Environmental and lifecycle
Operating temperature range from -50 to +60 °C, with temperature compensation active between -20 and +60 °C. Storage and transport range is -50 to +80 °C. That wide operating band covers unheated plant floors in winter and hot cabinet interiors in summer without derating the trip curve. Lifecycle status is current production. This order code is sourced and quoted to order against an RFQ through independent distribution.