The Siemens 3RV1042-4BA10 is a SIRIUS motor protection circuit breaker rated for 20 A continuous current with a Class 10 trip characteristic, meaning it will trip within 10 seconds at 7.2× the thermal setting — fast enough to protect standard induction motors from locked-rotor heat buildup without nuisance trips on normal starting inrush. Rated motor power is 7.5 kW at 400 V — that maps to a typical 10 HP or 15 A full-load motor on a 400 V line. The screw terminals accept solid 2x (2.5…16 mm²) and stranded up to 2x (10…50 mm²), so it lands comfortably on the wire sizes a 20 A motor circuit uses.
Mounting position any — no derating needed for horizontal or vertical orientation. Zero clearance at the sides and back means you can pack it tight against other devices in a row without heat-spacing gaps. Footprint is 70 mm wide × 165 mm tall × 174 mm deep. That 174 mm depth is the dimension to watch when sizing the gland plate or enclosure depth — it's deeper than a typical contactor, so a shallow 200 mm enclosure may be tight with wiring clearance.
Shock rated at 25g for 11 ms. Front IP20 — fine for a panel interior, not for washdown zones. RoHS compliance date listed as July 1, 2006, which aligns with the EU RoHS directive effective date. No UL or CSA marks in the evidence, but the IEC ratings (690 V, 100 kA) are standard for European-spec panels.