Motor protection circuit breaker for the panel builder
The Siemens 3RV2031-4TB15 is a SIRIUS motor protection circuit breaker designed for motor protection. It screws or snaps onto a 35 mm standard mounting rail per DIN EN 60715, so it integrates into any standard DIN-rail panel. Rated voltage spans 20 to 690 V, covering most low-voltage motor circuits. The Class 20 trip characteristic means it allows a longer starting current inrush — typical for high-inertia loads like conveyors or fans — before the thermal element opens.
Breaking capacity and coordination
At 240 V the interrupting rating hits 100 kA, which is high for a motor-protection device this compact. At 400 V it drops to 30 kA, and at 690 V to 3 kA. That 30 kA at 400 V is enough for most industrial panel feeders with standard upstream fuses or a molded-case breaker. The 3 kA at 690 V means it is not suited for high-fault 690 V distribution — you need upstream current-limiting protection there.
Mounting and wiring
Mounting position is any, which helps in tight enclosures. The main contact terminals accept M6 ring lugs, and the control wiring takes 2x 0.5 to 1.5 mm² or 2x 0.75 to 2.5 mm² solid or stranded. Clearance to grounded metal: 50 mm above and below, 10 mm to the side. That 10 mm side gap is tight — you can pack breakers close on the rail if the ambient stays under 60 °C.