What it is and what the ratings mean for fit
The Siemens SIRIUS 3RV1021-4DA10-ZW98 is a 3-pole motor protection circuit breaker rated at 25 A continuous current and 11 kW at 400 V AC-3, with a breaking capacity of 50 kA at 400 V. The Class 10 trip curve means it will clear a stalled-rotor condition fast enough to protect most standard induction motors before the winding insulation degrades — that's the critical spec for motor branch-circuit protection. Phase failure detection is built in, which is a requirement for preventing single-phasing damage on three-phase motors. The IP20 front protection means it's suitable for installation inside a closed panel; it's not rated for washdown or outdoor exposure. Mounting is via screw and snap-on onto 35 mm standard mounting rail per DIN EN 50022, with any mounting position allowed. The screw-type terminals accept solid or stranded conductors: 2x (1...2.5 mm²) and 2x (2.5...6 mm²) per pole, with AWG equivalents of 2x (14...10). Zero clearance is required at the back and sides — 0 mm backwards and 0 mm at the side — so it can be packed tight against adjacent devices on the rail without derating.
Where it fits in the panel
At 45 mm wide, 97 mm tall, and 96 mm deep, this breaker occupies a standard 45 mm module width on the DIN rail — one slot in a typical distribution panel. The auxiliary switch option (product extension auxiliary switch: Yes) means you can add a remote status contact without extra wiring to the main circuit. The 25 A continuous rating and 11 kW motor rating make it a direct fit for motor branch circuits feeding pumps, fans, or small conveyors up to that power level.