The Siemens 3RV5041-4FA10 is a SIRIUS-brand size S3 motor protection circuit breaker — thermal-magnetic, three-pole, rated 40 A operational current at 400 V AC-3 duty, 690 V max, 50/60 Hz. The magnetic short-circuit release handles fault interruption; the thermal bimetal tracks the motor heating curve. Panel clearance: 50 mm above and below, 30 mm at the sides, 167 mm forward. The 174 mm depth plus forward clearance means you need about 341 mm total depth inside the enclosure from the rail to the door or gland plate.
Rated 40 A at AC-3 (400 V) — that's the motor-switching current, not the resistive-heater rating. Class 10 trip class matches most IEC motor starting profiles up to about 18.5 kW at 400 V (ballpark, depends on motor data). The 20 W typical power loss is what the enclosure has to shed; if you pack several S3 frames in a small panel, derate or add ventilation. Surge voltage withstand is 6 kV, shock rated 25 g / 11 ms per IEC 60068-2-27. That's standard for industrial panel gear — no special handling needed for most machine-mounted applications.
RoHS compliance date is July 1, 2006 — it meets the EU RoHS directive. The SIRIUS series carries UL/CSA/CE/IEC approvals as a family; the 3RV5041-4FA10 is typically listed under UL 508 and IEC 60947-2/4. Compliance documentation (declaration of conformity, UL recognition) is available from Siemens on request.
Screw-type box terminals on top and bottom, accepting 2x (2.5…16 mm²) solid/stranded, 2x (10…50 mm²), or 1x (10…70 mm²). AWG equivalents: 2x (10…1/0) or 1x (10…2/0). Torque range 4…6 N·m. That's enough cross-section for the full 40 A circuit without paralleling conductors. Operating temperature -20…+60 °C, storage -50…+80 °C, humidity 10…95 %. Installation altitude max 2 000 m without derating.