Motor protection circuit breaker for 40 A lines
The Siemens SIRIUS 3RV1031-4FA10-ZW96 is a 3-pole motor protection circuit breaker rated 40 A continuous current, sized for a 18.5 kW motor at 400 V AC.
Rated breaking capacity at 400 V AC is 50 kA, dropping to 100 kA at 240 V and 10 kA at 500 V. That 50 kA at 400 V gives solid headroom for most industrial panel bus feeds — you can coordinate this downstream of a 63 A or 100 A molded-case without worrying about cascading failure.
Width is 55 mm, height 140 mm, depth 149 mm — fits a standard 6-module-wide footprint. Screw-type box terminals on the main circuit accept 2× (0.75…16 mm²) solid or 2× (0.75…25 mm²) stranded, with a single run up to 35 mm² stranded. That covers most motor feeder cables up to about 10 AWG in parallel or a single 2 AWG. Backwards and side clearance is 0 mm — you can butt it against adjacent devices on the rail.
Shock rated at 25 g for 11 ms. RoHS substance prohibition date is July 1, 2006, meaning the design complies with the original RoHS directive.
Power dissipation and auxiliary contacts
Total power dissipation in hot operating state is 29 W, or 9.7 W per pole. That matters for enclosure thermal rise — in a sealed panel with multiple breakers, you'll want to sum these and check against the cabinet's dissipation rating. The design accepts auxiliary switch modules (product extension auxiliary switch: yes), so you can add a remote status contact without replacing the breaker.