What this breaker does on your line
The Siemens 3RV2031-4DB15-ZX95 is a SIRIUS motor protection circuit breaker — the thing that sits between your contactor and the motor, watching for overload and short-circuit. Trip Class 20 means it lets a motor pull starting current for up to 20 seconds before tripping, which covers most standard induction motors on pumps, fans, and compressors. The 30 kA interrupting rating at 400 V means it can clear a bolted fault without upstream fuses needing to help — that's the number your panel SCCR study cares about. Mounts on 35 mm DIN rail per EN 60715, screw or snap-on, any orientation. At 55 mm wide it takes one standard module slot — leaves room for the contactor and overload block next to it. Rated for 20–690 V operating range, so it covers 400 V and 480 V common in industrial panels without derating.
Mounting and panel fit
Screw and snap-on mounting onto 35 mm DIN rail per DIN EN 60715. Mounting position any — horizontal, vertical, upside-down, doesn't care. Depth 149 mm, width 55 mm, height 140 mm. Clearance: 50 mm above and below, 10 mm at the sides, zero forward or backward. Main contact terminals take M6 screws; solid or stranded wire up to 2x 2.5 mm².