The Siemens SIRIUS 3RV1021-0FA10-ZW97 is a motor-protection circuit breaker rated for 0.5 A continuous current with a CLASS 10 trip curve, meaning it disconnects within 10 seconds at 7.2× rated current — fast enough to protect a 0.12 kW motor at 400 V from overload without nuisance tripping on startup inrush. Breaking capacity holds at 100 kA across the full voltage range (240 V to 690 V AC), so it can interrupt a bolted fault on a high-capacity distribution bus without cascading upstream — no need for a current-limiting fuse ahead of it in most panels.
Mounting and panel fit
Snap-on mounting onto 35 mm DIN rail per EN 50022; screw terminals accept 2× (1 to 2.5 mm²) solid or stranded, or 2× (2.5 to 6 mm²) — covers the wire sizes typical for a 0.5 A motor branch circuit. Width 45 mm, height 97 mm, depth 96 mm — fits a standard 45 mm-wide MCCB slot on a DIN-rail panel. No side or backward clearance needed for arc venting (0 mm at the side, 0 mm backwards), so it can be packed tight against adjacent devices. IP20 on the front; rated for any mounting position, operating -20 to +60 °C, storage -50 to +80 °C, shock 25g / 11 ms — rugged enough for machine-tool cabinets and conveyor lines.
Key features for the panel builder
Phase-failure detection built in — if one phase drops, the breaker trips, preventing single-phasing on the motor. Ground-fault detection is not included; that is handled separately by a residual-current device if needed. Auxiliary switch option is present (yes), so you can wire a remote status signal back to a PLC or indicator light. Main contacts rated for 100,000 mechanical operations typical. Rated insulation voltage 690 V, surge voltage resistance 6 kV — coordination with standard IEC 60947-2 motor-protection breakers. Power loss 5.5 W at rated current in hot state (1.8 W per pole).