Motor protection circuit breaker for 40 A loads
The Siemens SIRIUS 3RV1031-4FA10-ZW95 is a 3-pole motor protection circuit breaker rated at 40 A continuous current, with a Class 10 trip characteristic. It's sized for a 18.5 kW motor at 400 V AC, making it a common choice for medium-horsepower pump, fan, and conveyor drives in control panels. The screw-type terminals accept up to 35 mm² stranded conductor, and the unit snaps onto a standard 35 mm DIN rail per EN 50022.
What the ratings mean for fit
The 40 A continuous rating and 18.5 kW at 400 V set the upper bound for motor size this breaker protects. The Class 10 trip means it will clear a locked-rotor condition within 10 seconds at 7.2× rated current, which is standard for standard induction motors — no need for a slower Class 20 unless you're starting high-inertia loads. The breaking capacity is 50 kA at 400 V AC, so it handles substantial fault currents without upstream coordination issues in most industrial panels. Phase failure detection is built in; ground fault detection is not, so if you need that, you'll add a separate module or relay.
Panel integration and wiring
Mounts on 35 mm DIN rail with the screw-and-snap method; no tools needed for the snap action. Dimensions are 55 mm wide, 140 mm high, 149 mm deep — figure that into your DIN rail layout and enclosure depth. The screw terminals accept 2x (0.75–16 mm²) solid or 2x (0.75–25 mm²) stranded, with a single terminal taking up to 35 mm² stranded. That's enough for the incoming feeder and motor leads. IP20 on the front means it's protected against finger contact but not washdown — keep it inside a closed panel.
Compliance and environmental
The substance prohibitance date of 07/01/2006 aligns with RoHS compliance (RoHS took effect July 2006). The surge voltage resistance is rated at 6000 V, and the operating temperature range is -20 to +60 °C. Storage and transport range is -50 to +80 °C. Shock resistance is 25g for 11 ms, so it holds up in moderate vibration environments.