Motor protection circuit breaker — 10 A, CLASS 10, 100 kA
The Siemens SIRIUS 3RV1021-1JA15-ZW97 is a motor protection circuit breaker rated for 10 A continuous current and 4 kW at 400 V AC. It's built for protecting three-phase induction motors up to that load, with CLASS 10 trip characteristics — meaning it will trip within 10 seconds at 7.2× rated current, fast enough to protect standard motors during locked-rotor conditions without nuisance tripping on startup. Breaking capacity is 100 kA at 240 V and 400 V AC, dropping to 42 kA at 500 V and 6 kA at 690 V. That 100 kA figure at 400 V is high for this class — it handles high-fault utility feeds without needing an upstream current-limiting fuse in most panel designs. Phase failure detection is built in, so if one phase drops on the line side, the breaker trips — critical for preventing single-phasing damage on delta-connected motor loads. No ground fault detection on this unit, so that's a separate device if needed.
Mounting and panel fit
Mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 50022. At 45 mm wide, it takes a single 9 mm module width on the rail. Depth is 96 mm, height 97 mm — standard SIRIUS footprint, so it drops into existing Siemens motor starter assemblies or standalone DIN-rail enclosures without panel rework. Mounting position is any orientation, and the front face carries IP20 finger-safe protection — fine for enclosed panels, not for washdown zones.
Termination and aux contacts
Main circuit terminals are screw-type, accepting solid conductors 2× (0.5 to 1.5 mm²) and 2× (0.75 to 2.5 mm²), or stranded 2× (1 to 2.5 mm²) and 2× (2.5 to 6 mm²). That covers most motor power wiring up to 4 mm² — typical for a 10 A motor circuit. An auxiliary switch is included, rated 1 A at 24 V, 0.5 A at 230 V, 0.15 A at 60 V. The auxiliary switch design is transverse. No additional auxiliary contact blocks are fitted (: 0 for auxiliary contacts).