What it is and what it does
The Siemens SIRIUS 3RV1021-4DA10-ZI41W96 is a motor protection circuit breaker sized for a 25 A continuous load, rated 11 kW at 400 V in AC-3 duty — the standard motor-switching category. Trip Class 10 means it clears an overload within 10 seconds at 7.2× the thermal setting, which is the usual spec for standard induction motor starts. Phase failure detection is built in, so it catches a lost leg before the motor cooks.
Breaking capacity and selectivity
The interrupting rating is 50 kA at 400 V AC, which covers most industrial service-entrance and sub-distribution fault levels without needing an upstream current-limiting fuse. At 240 V it rises to 100 kA; at 500 V it drops to 10 kA, and at 690 V to 4 kA. If your panel's available fault current sits above 50 kA at 400 V, you'll need to coordinate upstream — the breaker itself won't be the weak link in the selectivity study.
Mounting and wiring
Mounts on 35 mm DIN rail per EN 50022, screw and snap-on. Any orientation works. The 45 mm wide footprint matches the standard SIRIUS 3RV1 compact frame — it'll drop into the same DIN-rail slot as the 3RV6021-4DA10 without panel rework. Screw terminals on both main and auxiliary circuits; accepts 1–2.5 mm² solid or stranded, or 2.5–6 mm² on the larger clamping range. Strip length is the usual 8–10 mm for this terminal family.
Environmental and mechanical
Runs from -20 to +60 °C; stores or ships from -50 to +80 °C. Front face is IP20 — finger-safe but not washdown-rated. Shock-rated to 25 g at 11 ms, which is enough for most conveyor and machine-tool applications. Mechanical life is 100,000 operations typical on the main contacts.