What this SIRIUS breaker is and what it does
The Siemens 3RV1011-0FA20-ZX95 is a SIRIUS motor protection circuit breaker sized for small motors up to 0.12 kW at 400 V. It's rated at 0.5 A continuous current with a CLASS 10 trip characteristic, meaning it will trip fast enough to protect a standard induction motor during a stall or locked-rotor event — that's the trip class you want for most general-purpose motor starts. The breaker's 100 kA breaking capacity holds all the way from 240 V through 690 V AC, so it can sit on a high-fault panel bus without needing an upstream current-limiting fuse for most installations. It also has phase failure detection built in, which keeps a motor from single-phasing and burning out — a common failure mode in small shops where a fuse blows on one leg and nobody notices until the motor smells hot.
Panel fit and wiring
Mounts on a 35 mm DIN rail per DIN EN 50022, either screwed down or snapped on. The 45 mm width means it takes up one standard 45 mm module slot — no surprises in a crowded panel. Height is 90 mm and depth is 81 mm, with 0 mm clearance needed at the back or sides. That zero-clearance spec means you can butt it against other devices on the rail without worrying about heat buildup or arc flash gaps. Wiring is all spring-loaded terminals — both the main circuit and the auxiliary/control circuit. Solid conductors from 0.25 to 2.5 mm² or finely stranded with ferrule from 0.25 to 1.5 mm². AWG equivalents are 24 to 14 for the main contacts. The front is IP20 finger-safe and touch protection is rated finger-safe, so it's safe to work around live in a locked panel.