What this part is and what it does
The Siemens SIRIUS 3RV2021-4BA15-0BA0 is a motor-protective circuit breaker designed for motor protection in industrial control panels. It provides Class 10 trip characteristics, meaning it disconnects within 10 seconds at 7.2× the thermal setting — fast enough to protect standard induction motors during locked-rotor starts without nuisance tripping on normal acceleration. Rated at 5.5 kW at 230 V, it covers small-to-medium motor loads common on conveyor drives, pumps, and fans. Phase failure detection is built in, so a lost phase on the line side trips the breaker and prevents single-phasing damage. Mounts via screw and snap-on onto 35 mm DIN rail per DIN EN 60715, with any mounting position allowed. The 45 mm width fits standard panel spacing; depth is 97 mm, which clears most shallow enclosures.
Short-circuit ratings and selectivity
The interrupting ratings are the deciding factor for panel SCCR compliance: 100 kA at 240 V, 25 kA at 400 V, 5 kA at 500 V, and 2 kA at 690 V. The 25 kA at 400 V is the most common industrial service voltage — this breaker can sit upstream of a smaller branch device without needing a current-limiting fuse ahead of it, as long as the available fault current stays under that threshold. For gG fuse-listed backup protection, the rated values are 63 A at 400 V, 50 A at 500 V, and 50 A at 690 V — relevant when coordinating with a downstream motor starter or soft starter.
Lifecycle and sourcing posture
Termination is screw-type terminals for the main current circuit, accepting 2×(0.5–1.5 mm²) or 2×(0.75–2.5 mm²) solid or stranded. The M4 main-contact screws are standard for panel wiring.