What it is and what it does
The Siemens SIRIUS 3RV1021-1FA15-ZW95 is a motor protection circuit breaker designed for the main current circuit of three-phase motors. It provides phase-failure detection and thermal-magnetic overload protection with a CLASS 10 trip characteristic, sized for a 5 A continuous rated current and rated to switch a 1.5 kW motor at 400 V.
Breaking capacity and fault clearing
Rated short-circuit breaking capacity reaches 100 kA at 240 V, 400 V, and 500 V AC, dropping to 6 kA at 690 V AC. The 100 kA figure at 400 V means this breaker can safely clear a high-fault-current event on a motor branch without upstream fuses needing to coordinate — a real advantage in panel designs where SCCR must hit 100 kA without a separate current-limiting device.
Mounting and panel integration
Mounts via screw fixing or snaps onto 35 mm DIN rail per DIN EN 50022. The 45 mm width and 97 mm height fit a standard single-module footprint; depth is 96 mm. Any mounting position is permitted, and zero clearance is required at the sides or rear, so it can be packed tightly in a crowded enclosure.
Terminals and wiring
Screw-type terminals on both the main and auxiliary circuits. The main contacts accept solid conductors 2x (0.5…1.5 mm²) and 2x (0.75…2.5 mm²), stranded 2x (1…2.5 mm²) and 2x (2.5…6 mm²), plus AWG 2x (14…10). The auxiliary switch is transverse and rated 1 A at 24 V, 0.5 A at 230 V, 0.15 A at 60 V.