What this SIRIUS breaker does and where it fits
The Siemens 3RV1031-4HB15-ZX95 is a SIRIUS motor protection circuit breaker designed for protecting three-phase induction motors against overload, short-circuit, and phase failure. It carries a continuous current rating of 50 A and delivers 22 kW at 400 V in AC-3 duty — the rating that governs real motor switching, not just resistive load. Trip Class 20 means it allows a longer start-up time for high-inertia loads like fans or conveyors before tripping on overload. Phase failure detection is built in, so if one line drops, the breaker trips before single-phasing damages the motor. No ground-fault detection on this variant — that's handled separately in the circuit if required. Mounts via screw and snap-on onto 35 mm DIN rail per DIN EN 50022. Any mounting position is acceptable, which simplifies panel layout. The front face is IP20 rated — protected against finger contact but not washdown; keep it inside an enclosure.
Short-circuit breaking capacity — what it interrupts
The interrupting rating varies with line voltage: 100 kA at 240 V AC, 50 kA at 400 V AC, 10 kA at 500 V AC, and 4 kA at 690 V AC (–). At 400 V, that 50 kA SCCR means it safely clears a bolted fault up to that level without the arc flashing over or the case rupturing — critical for panel coordination studies.
Termination and wiring
Main circuit terminals are screw-type with box terminals. Accepts stranded wire: 2x (0.75... 25 mm²) or 1x (0.75 … 35 mm²). Solid wire: 2x (0.5... 1.5 mm²) or 2x (0.75... 2.5 mm²). AWG equivalents for main contacts: 2x (18... 2) or 1x (18... 2). Auxiliary and control circuit also use screw-type terminals.
Environmental and compliance
RoHS compliance dated to 07/01/2006. Operating temperature range -20 to +60 °C; storage and transport -50 to +80 °C. Shock rated at 25g / 11 ms. Power dissipation in hot operating state: 29 W.