What it is and what it does
The Siemens 3RV1011-1BA25 is a SIRIUS motor protection circuit breaker sized for a 0.75 kW motor at 400 V AC three-phase. Its 2 A continuous current rating and CLASS 10 trip characteristic mean it protects standard induction motors against overload and short-circuit without nuisance tripping on normal startup inrush. Breaking capacity hits 100 kA at 400 V AC — that's high enough to sit upstream of most distribution panels without needing a separate backup fuse. At 690 V it still interrupts 2 kA, which covers the fault current available in most industrial motor branches.
Mounting and wiring
Mounts on 35 mm DIN rail per EN 50022 or screws to a backplate. Width is 45 mm. Spring-loaded terminals accept 0.25 to 2.5 mm². Mounts in any orientation, and the IP20 finger-safe front means it can sit near the cabinet door without a separate cover. Keep 0 mm clearance at the back and sides — no derating for side-by-side stacking in a standard enclosure.
What the ratings mean in practice
The CLASS 10 trip curve means the bimetal releases in under 10 seconds at 7.2× rated current — fast enough to protect a standard 4-pole motor winding during a stall, slow enough to let it start a high-inertia fan or pump without nuisance trips. Phase-failure detection is built in, so a lost phase on the line side trips the breaker instead of cooking the motor on single-phase current. Rated operational power of 0.75 kW at 400 V AC-3 matches a standard 1 HP IEC motor. The auxiliary switch option (transverse design) lets you wire a remote fault indication or a holding circuit without adding a separate contactor block. Spring-loaded terminals accept AWG 24 to 14 — common for North American control wiring. The 7.25 W power dissipation at rated current is low enough that multiple breakers can be ganged in a sealed enclosure without active cooling, as long as ambient stays under 60 °C.