What this breaker does on a motor branch
The Siemens SIRIUS 3RV2331-4RC10 is a circuit breaker purpose-built for starter combinations — it sits upstream of a contactor in a motor branch, providing short-circuit and overload protection in one package. At 230 V it's rated for 22 kW motor loads, and it covers the full voltage range from 20 to 690 V, so it adapts to whatever line voltage the plant throws at it.
Mounting and wiring — panel fit
Any orientation. Screw terminals accept up to 2x 35 mm² or 1x 50 mm². Clearances: 50 mm above and below, 10 mm sides, zero forward or backward. Depth is 149 mm.
Breaking capacity by voltage — the selectivity story
The breaking capacity isn't a single number — it varies with system voltage. At 240 V it's rated for 100 kA, at 400 V it drops to 30 kA, at 500 V it's 5 kA, and at 690 V it holds at 2 kA. The 2 kA at 690 V is enough for most 690 V motor circuits, but verify your available fault current if you're close to the transformer.