What it is and what it does
The Siemens 3RV1031-4HA10 is a SIRIUS motor protection circuit breaker, designed to protect motor branch circuits against overloads and short circuits. It's rated for 50 A continuous current and handles a 22 kW motor at 400 V, with a Class 10 trip curve that clears overloads fast enough for standard induction motors — meaning it'll trip before the windings cook on a stalled rotor. Three-pole design with screw-type box terminals on the main circuit and separate screw terminals for the auxiliary/control circuit. It snaps onto a 35 mm DIN rail per EN 50022 and can be mounted in any position — handy when you're cramming gear into a tight panel. Breaking capacity is 100 kA at 240 V AC, 50 kA at 400 V, 10 kA at 500 V, and 4 kA at 690 V — so it'll handle a stiff fault on a 400 V distribution board without welding its contacts shut.
Key ratings and what they mean for fit
The 50 A continuous rating and 22 kW at 400 V tell you this breaker is sized for a motor drawing around 50 A full load — typical for a 22 kW four-pole induction motor on 400 V three-phase. The Class 10 trip characteristic means it allows a short starting inrush (up to about 10 seconds at 7x FLA) before tripping, which covers most standard motor starts without nuisance trips. Phase failure detection is built in — if one phase drops out, the breaker will trip, preventing single-phasing damage. No ground fault detection on this variant, so if you need that, you'll add an external module or choose a different SIRIUS version. Power dissipation runs 29 W hot at rated current, or about 9.7 W per pole. That's heat that has to leave the enclosure — factor it into your panel thermal calculations, especially if you're stacking several breakers side by side. Surge voltage resistance is 6 kV, meaning it's designed for installation environments where impulse voltages from switching or lightning can hit the line — typical for industrial control panels.
Where it goes and how it mounts
Snap-on mounting onto 35 mm DIN rail per DIN EN 50022 — standard for any European-style panel. Zero clearance needed at the sides or back, so you can butt it against other devices without derating for air gaps. Dimensions: 55 mm wide, 140 mm tall, 149 mm deep. That 149 mm depth includes the screw terminals and any protruding wiring — check your enclosure depth before committing, especially if there's a door-mounted HMI or disconnect behind it. Wire capacity is generous: solid conductors up to 2x 16 mm², stranded up to 2x 25 mm² or 1x 35 mm² with a ferrule. That covers most motor feeder cables up to 50 A without needing oversized lugs. IP20 on the front — finger-safe touch protection, so it's fine in a closed panel but not washdown-rated. Keep it dry. Shock rated at 25 g for 11 ms — it'll survive a forklift bump to the panel or a nearby press hitting the floor. Operating temp range -20 to +60 °C, storage/transport -50 to +80 °C.
Lifecycle and sourcing
The auxiliary switch option is available as a field-addable accessory — the breaker is designed for it (product extension auxiliary switch: Yes). No need to order a different base unit if you later add signaling.