What it is and what it does
The Siemens 3RV1021-1KA10-ZW97 is a SIRIUS motor protection circuit breaker, 3-pole, rated for 12.5 A continuous current and 5.5 kW at 400 V. It's designed to protect motor circuits from overloads and short circuits, with a Trip Class 10 — meaning it will trip within 10 seconds at 7.2× the thermal setting, matching standard IEC motor starting curves for direct-on-line induction motors up to that power. Phase failure detection is built in, so a single-phase condition on a three-phase motor will trip the breaker — a common failure mode in field service that can burn out a winding before the overload relay notices. No ground fault detection on this variant.
Breaking capacity and where it fits
Breaking capacity is 100 kA at both 240 V and 400 V AC, dropping to 42 kA at 500 V and 6 kA at 690 V. That 100 kA at 400 V means this breaker can clear a fault on a high-capacity distribution board without upstream fuses needing to coordinate — useful when you're dropping this into a panel fed by a transformer with high short-circuit current. Mounts via screw and snap-on onto standard 35 mm DIN rail per DIN EN 50022. The 45 mm width means it takes up a single modular slot on the rail. Screw-type terminals on both main and auxiliary circuits — field-service friendly, no special crimp tool needed.
Wiring and ratings at a glance
Terminals accept solid or stranded wire: 2 conductors of 1 to 2.5 mm², or 2 conductors of 2.5 to 6 mm². For AWG, that's 2x 14-10 AWG. The depth is 96 mm, height 97 mm — fits standard shallow enclosures. IP20 on the front panel — protected against finger contact, but not against water ingress, so mount inside a rated enclosure in wet environments. Operating temperature -20 to +60 °C; storage and transport -50 to +80 °C. Maximum operating frequency in AC-3 duty is 15 operations per hour — that's fine for a pump or conveyor starting a few times an hour, but not for a rapid-cycling application like a press or a crane.