Motor Protection Circuit Breaker — SIRIUS 3RV2021-4BA40
The Siemens 3RV2021-4BA40 is a SIRIUS-branded motor protection circuit breaker designed for motor protection duty. It carries a Trip Class 10 rating, meaning it will trip within 10 seconds at a locked-rotor current of 7.2× setting — the standard for standard-duty induction motor starts up to about 15 starts per hour. Breaking capacity is 100 kA at 240 V AC, 25 kA at 400 V, 5 kA at 500 V, and 2 kA at 690 V. At 400 V, the recommended back-up fuse is gL/gG 63 A; at 500 V and 690 V it drops to gL/gG 50 A. This tells you the SCCR your panel can claim when this breaker is the branch-circuit protector — coordination matters upstream. Phase failure detection is built in; ground fault detection is not. If your motor starter needs GF protection, you'll add a separate module or relay downstream.
Mounting and Integration
Mounts via screw and snap-on onto 35 mm DIN rail per DIN EN 60715. Any mounting position is allowed. The 45 mm width matches the standard SIRIUS 3RV2 frame — it occupies one slot in a multi-breaker panel layout. Main circuit connection uses ring cable lugs at M4 screws. Clearance distances: 50 mm upwards and downwards, 30 mm at the side, 0 mm forwards and backwards. That 0 mm backwards means it can sit flush against a backplane or another device — useful in dense panels.
Environmental and Operational Range
Operating temperature range is -20 to +60 °C; storage and transport range is -50 to +80 °C. The storage limit governs handling and warehousing, not running conditions. Switching frequency at AC-3 and AC-3e maximum duty is 15 operations per hour. For higher-duty-cycle applications like frequent jogging or reversing, a larger frame or contactor-based starter may be necessary.
Motor Horsepower Ratings
This breaker is rated for motor loads at standard North American voltages: 3 hp at 230 V, 5 hp at 220/230 V, 7.5 hp at 200/208 V, and 10 hp at 460/480 V. At 110/120 V it covers 1.5 hp. These are useful for direct cross-reference to NEMA motor tables.