What it is and what it does
The Siemens 3RV1021-0HA15-ZW97 is a SIRIUS motor protection circuit breaker designed for motor protection, rated at 0.8 A continuous current with a Class 10 trip characteristic — meaning it trips fast enough to protect standard induction motors during a locked-rotor event without nuisance tripping on normal starting inrush. Phase failure detection is built in, so if one leg drops on a three-phase motor, the breaker opens before single-phasing cooks the winding. Breaking capacity hits 100 kA at 240 V, 400 V, 500 V, and 690 V AC — that's a high-fault rating for a 45 mm wide device, meaning it can sit upstream of a high-available-fault panel without needing a current-limiting fuse ahead of it.
Mounting and wiring
Snaps onto a 35 mm DIN rail per DIN EN 50022, or screws directly to a backplate — any mounting position works, so panel layout is flexible. Main circuit terminals accept solid wire 2x (0.5 to 1.5 mm²) and 2x (0.75 to 2.5 mm²), or stranded 2x (1 to 2.5 mm²) and 2x (2.5 to 6 mm²) — covers the range you'd expect for a 0.8 A motor branch. Auxiliary and control circuits use screw terminals as well, and the auxiliary switch is a transverse design — it's field-addable, so you can wire in a remote status signal without swapping the whole breaker. IP20 on the front means it's touch-safe for the panel builder; no washdown rating here, so keep it inside the enclosure.
Lifecycle and sourcing
RoHS compliance date is 01.05.2012, so it's been REACH/RoHS-conformant for over a decade; no substance-prohibition surprises for EU-bound panels.