Motor Protection Breaker, 40 A, Class 10 — SIRIUS 3RV1031-4FA10
It carries a 50 kA short-circuit breaking capacity at 400 V AC and is rated for 18.5 kW motor load at 400 V, so it can handle a direct-on-line motor start on a typical 400 V three-phase supply without needing an upstream fuse for fault levels up to 50 kA.
At 55 mm wide, 140 mm tall, and 149 mm deep, it takes up one standard modular slot — no surprises when laying out a row of motor starters. Screw-type box terminals on the main circuit accept 2x 0.75–16 mm² solid or 2x 0.75–25 mm² stranded, and the auxiliary circuit also uses screw terminals — standard stuff for a panel shop, no special tooling needed.
Power dissipation runs 29 W total in hot operating state, or 9.7 W per pole — worth checking the thermal budget in a densely packed enclosure, especially if you're stacking several of these next to each other. The IP20 front protection is typical for a DIN-rail device inside a locked panel; it keeps fingers out but isn't rated for washdown environments. RoHS compliance date of 07/01/2006 means it meets the EU substance restrictions for lead, mercury, cadmium, and the usual six — no compliance surprise for a European-built machine.