What it is and where it fits
The Siemens 3RV2331-4KC10 is a SIRIUS circuit breaker designed specifically for starter combinations — meaning it integrates directly into a motor starter assembly, combining short-circuit and overload protection in one device. It mounts via screw and snap-on onto 35 mm DIN rail per DIN EN 60715, so it lands in any standard control panel without extra bracketry.
Key ratings — what they mean for your panel
Rated breaking capacity at 400 V is 30 kA — that's the fault current it can safely interrupt without welding contacts or cascading damage upstream. For a 480 V system the breaking capacity is 65 A (not kA — that's the continuous current rating at that voltage), so at higher voltages the part carries less continuous load. Motor power rating at 230 V is 22 kW, at 460/480 V it's 50 hp, at 575/600 V it's 60 hp — match these to your motor nameplate, not the line voltage alone.
Clearances and integration
Clearance distances are tight: 50 mm upwards and downwards, 10 mm sideways, zero forwards and backwards. That means you can pack breakers side-by-side on the DIN rail with only 10 mm between units, but leave 50 mm above and below for arc venting and cable bend radius. Terminal capacity accepts 2x 1–35 mm² or 1x 1–50 mm² solid/stranded — sized for motor feeder cables up to 50 mm².