What it is and what it does
The Siemens 3RV2021-0JA15 is a SIRIUS motor protection circuit breaker designed to protect motors against overloads and short circuits. Its Trip Class 10 means it will trip within 10 seconds at 7.2× the thermal setting, matching the startup profile of standard induction motors — pumps, fans, compressors — without nuisance tripping on inrush. Rated for 20 to 690 V AC, it delivers a 100 kA breaking capacity at 400 V, 500 V, and 690 V, so it can safely interrupt high-fault currents in industrial distribution panels without upstream fuses or larger breakers. At 230 V it is rated for 0.2 kW motor loads; at 575/600 V it covers 0.5 hp. Phase failure detection is built in — if one phase drops, the breaker trips, preventing single-phasing damage to the motor. Ground fault detection is not included, so a separate ground-fault relay is needed if that protection is required.
Mounting and integration
Mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 60715. The 45 mm width and 97 mm depth fit standard panel layouts; any mounting position is allowed, so it can be oriented vertically or horizontally to suit gland-plate clearance. Main circuit terminals are M4 screw-type, accepting 2× (0.5 to 1.5 mm²) or 2× (0.75 to 2.5 mm²) solid or stranded wire. The 50 mm clearance above and below the unit (no side clearance needed) simplifies wiring in dense panels.