Motor protection breaker for the wet line
The Siemens SIRIUS 3RV2021-4EA20-0BA0 is a motor protection circuit breaker in the S0 frame, designed to protect three-phase motors from overload and short-circuit conditions. It carries a CLASS 10 trip class, meaning it will trip within 10 seconds at 7.2× the set current — fast enough to protect standard induction motors during a stalled-rotor start, but not so fast that it nuisance-trips during a normal acceleration. The adjustable overload release covers 27 to 32 A, and the fixed magnetic short-circuit release fires at 400 A. Rated operational current is 32 A, and the breaker handles fault currents up to 100 kA at 240 V, 25 kA at 400 V, 5 kA at 500 V, and 2 kA at 690 V. That 100 kA figure at 240 V is the headline number — it means this breaker can sit upstream of a motor starter on a high-capacity distribution board without needing a current-limiting fuse ahead of it, as long as the prospective short-circuit current at that point stays under 100 kA. The spring-type terminals accept solid or stranded copper up to 10 mm², and the breaker snaps onto a 35 mm DIN rail per DIN EN 60715. It is rated for 500 switching cycles at an ambient temperature down to -50 °C, which covers outdoor or cold-store installations.