The Siemens SIRIUS 3RV1021-0FA10-ZX95 is a motor protection circuit breaker designed for 0.5 A continuous current in AC-3 duty, with a CLASS 10 trip characteristic that clears overloads before the motor windings exceed thermal limits — every shot the same, no scrap on the floor from nuisance trips or missed faults. Rated breaking capacity holds at 100 kA across the full voltage range: 240 V, 400 V, 500 V, and 690 V AC, so it safely interrupts faults up to that level without cascading upstream — a single breaker covers the panel's SCCR requirement. Mounts via screw or snap-on onto 35 mm standard mounting rail per DIN EN 50022, with zero clearance required at the sides or rear — 45 mm wide, 97 mm tall, 96 mm deep, fitting tight gland-plate layouts without derating.
Motor protection and trip coordination
Phase failure detection is built in — the breaker trips on loss of any phase, preventing single-phasing damage on a 0.12 kW motor at 400 V. That's the spec that keeps the line running when a contactor drops a leg. Trip class CLASS 10 means it clears overloads within 10 seconds at 7.2× the set current, matching the thermal curve of standard IEC induction motors. For a 0.5 A motor branch, that's the difference between a coordinated trip and a welded contactor. Mechanical endurance rated at 100,000 operations of the main contacts.
Termination and wiring
Main circuit terminals are screw-type, accepting 2× (1 … 2.5 mm²) solid or 2× (2.5 … 6 mm²) stranded, with AWG equivalents 2× (14 … 10). Finely stranded conductors with core-end processing use the same ranges. An auxiliary switch is available as an add-on (not included in the base unit), letting the breaker signal its trip state back to a PLC or status lamp without a separate control relay.
Environmental and installation constraints
Operates from -20 °C to +60 °C, stores and transports from -50 °C to +80 °C — fine for unheated warehouses or roof-mounted enclosures in temperate climates. Shock rated at 25 g for 11 ms, so it holds calibration on a press or conveyor with intermittent vibration. Mounting position is any orientation, simplifying panel layout. Front face is IP20 — finger-safe but not washdown-rated; install inside a sealed enclosure if the panel sees coolant mist or washdown spray.