What this SIRIUS breaker does on a motor circuit
The Siemens 3RV2011-1KA25-ZX95 is a SIRIUS motor protection circuit breaker in the compact S00 frame, designed to sit upstream of a contactor on a motor branch. It combines a thermal overload relay (CLASS 10 trip curve) with a magnetic short-circuit release in one DIN-rail-mountable unit. The adjustable overload range is 9...12.5 A, and the instantaneous magnetic trip fires at 163 A — meaning it clears a bolted fault fast enough to protect the contactor and cable, not just the motor. Rated operational voltage covers 20...690 V. The interrupting capacity is 100 kA at 240 V and 400 V AC, dropping to 42 kA at 500 V and 6 kA at 690 V AC. That 100 kA at 400 V is the number that matters for most industrial panels — it handles high-fault-current plant networks without needing a current-limiting fuse upstream.
Termination and panel fit
Spring-type terminals on the main circuit and auxiliary contacts — no screwdriver needed for the power wiring, which speeds up panel assembly. The S00 footprint (45 mm wide, 97 mm deep) snaps onto 35 mm DIN rail per DIN EN 60715. The -ZX95 suffix adds a factory-fitted transverse auxiliary switch block with 1 NO + 1 NC contact, so you don't need a separate side-mount module for status feedback to the PLC.
What CLASS 10 means for motor starting
CLASS 10 means the overload element trips within 10 seconds at 600% of the set current. That's the standard for standard-duty induction motors — pumps, fans, conveyors that accelerate to full speed in a few seconds. It won't nuisance-trip on a normal start, but it clears quickly if the rotor locks. For high-inertia loads (centrifuges, flywheels) you'd want CLASS 20 or 30; for submersible pumps or hermetic compressors, CLASS 10 is the right call.