The Siemens SIRIUS 3RV2021-4BA15-ZW97 is a motor protection circuit breaker designed for motor protection duty. It carries a Class 10 trip characteristic, meaning it will trip within 10 seconds at 7.2× the thermal setting — fast enough to protect a standard induction motor during a locked-rotor event without nuisance tripping on normal starts. Phase failure detection is built in, so a lost phase on the line side triggers a trip before single-phasing cooks the winding.
Mounting and integration
Mounts via screw and snap-on onto 35 mm standard mounting rail per DIN EN 60715. The 45 mm width and 97 mm depth fit a standard 45 mm slot in a motor control center or panel; any mounting position is allowed. Screw-type terminals on the main current circuit accept 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) solid or stranded conductors, with M4 screws for the main contacts.
Breaking capacity and coordination
Rated short-circuit breaking capacity varies with line voltage: 100 kA at 240 V, 25 kA at 400 V, 5 kA at 500 V, and 2 kA at 690 V. At 400 V the gL/gG fuse backup rating is 63 A; at 500 V and 690 V it drops to 50 A. For a panel designer coordinating with upstream fuses or a molded-case breaker, these numbers define the selectivity window — the 25 kA at 400 V covers most industrial distribution systems without requiring a current-limiting upstream device.