The Siemens SIRIUS 3RV2021-4DA10-ZX95 is a motor protection circuit breaker designed for overload and short-circuit protection of motors up to 15 hp at 460/480 V. Its Trip Class 10 characteristic means it trips within 10 seconds at 7.2× rated current — the standard for standard-duty induction motor starts where the inrush decays quickly enough to avoid nuisance trips on a healthy start.
Breaking capacity and coordination
Rated breaking capacity hits 25 kA at 400 V AC, which covers most industrial panel fault levels up to that voltage. At 690 V it drops to 2 kA — still enough for many 690 V distribution points, but verify the prospective short-circuit current at that voltage. The 100 kA at 240 V means it can sit behind a larger upstream fuse without needing a current-limiting device in low-voltage residential or light commercial panels. Phase-failure detection is built in, so a lost phase on the supply side will trip the breaker before the motor single-phases to failure. Ground-fault detection is not included — that requires an external GFCI or residual-current device downstream.
Mounting and dimensions
Mounts via screw fixing or snap-on onto 35 mm DIN rail per DIN EN 60715. The 45 mm width matches the standard SIRIUS 3RV2 compact footprint — one 45 mm slot on the rail. Depth is 97 mm, which fits most standard enclosures with 120 mm or deeper back panels. Clearance requirements: 50 mm above and below, 30 mm to the side, zero forward or backward — so you can pack breakers tightly in a row as long as vertical airflow is maintained. Screw-type terminals on the main current circuit accept 2×(1…2.5 mm²) or 2×(2.5…10 mm²) solid or stranded conductors. Main contact screws are M4. Any mounting position is allowed, which simplifies panel layout.