The Siemens 3RV2021-1EA20-0DA0 is a SIRIUS S0-frame circuit breaker designed for system protection — think of it as the main disconnect or feeder protection in a motor control center, not a dedicated motor starter protector. It carries a 100 kA short-circuit breaking capacity at 240 V, 400 V, and 500 V AC, dropping to 4 kA at 690 V AC. That 100 kA rating at 400 V is the number that matters for most industrial panels: it means this breaker can safely interrupt a fault up to that level without cascading upstream, which is critical for selective coordination in a distribution board. Trip Class 10 means it clears a locked-rotor overload within 10 seconds at 7.2× the thermal setting — standard for protecting standard induction motors on pumps, fans, and conveyors. The 45 mm width and 97 mm depth fit the S0 footprint, and it snaps onto 35 mm DIN rail per DIN EN 60715, so it drops into any standard panel without extra bracketry.
Mounting and integration
Mounts in any position on 35 mm DIN rail. The spring-loaded terminals on the main current circuit accept 2× (1 to 10 mm²) solid or stranded wire — no lug crimping needed for most panel feeds. Clearance: 50 mm above and below, 30 mm to the side, zero forward or backward. That 50 mm upward clearance is the one to watch if you're stacking breakers in a tight enclosure; it keeps the arc chute venting unobstructed.