Motor protection circuit breaker for 400 V line-side coordination
The Siemens SIRIUS 3RV2021-4PA15 is a motor protection circuit breaker designed for CLASS 10 trip characteristics, meaning it clears a stalled-rotor overload within 10 seconds at 7.2× the thermal setting — fast enough to protect standard IEC induction motors without nuisance tripping on normal starts.
At 240 V the rating jumps to 100 kA, so on lower-voltage systems it handles virtually any utility fault. For 500 V and 690 V systems the SCCR drops to 3 kA and 2 kA respectively, which means upstream fusing or a current-limiting breaker is needed on those voltage classes. The 400 V 10 kA figure is the one most European industrial panels will care about; it matches typical transformer sizes up to 1.6 MVA.
DIN rail fit and terminal wiring
The 45 mm width occupies two standard 22.5 mm module slots, leaving room for an auxiliary contact block alongside. Main circuit terminals accept 2× (0.5 … 1.5 mm²) or 2× (0.75 … 2.5 mm²) solid or stranded copper, with M4 screw terminals. That 70 mm vertical breathing zone is enough for most enclosure layouts; keep it free for arc-flash venting and cable bend radius.