Motor protection breaker for the SIRIUS line
The Siemens SIRIUS 3RV2021-4BA25-ZX95 is a motor protection circuit breaker designed to clear overloads and short circuits in motor branch circuits. It carries a 25 kA SCCR at 400 V AC, which means it can safely interrupt a fault current up to that level without upstream fuses or breakers needing to clear first — that is the rating that decides coordination in a panel. Trip Class 10 means it trips within 10 seconds at 7.2x rated current, fast enough to protect standard induction motors during a locked-rotor event. Phase failure detection is built in, so a dropped phase on the line side will trip the breaker rather than letting the motor single-phase and overheat.
DIN-rail fit and terminal style
Mounts via screw and snap-on onto 35 mm DIN rail per DIN EN 60715 — the standard rail in any IEC panel. Mounting position is any orientation, which helps when fitting into tight gland-plate areas or vertical bus drops. The main circuit uses spring-loaded terminals accepting 2x 0.5 to 2.5 mm² solid or stranded; no screw torque to verify, no loosening under vibration. Dimensions are 45 mm wide, 97 mm deep, 119 mm high — this is a standard-width SIRIUS breaker that occupies one 45 mm slot on the rail, leaving the adjacent slots for contactors or overload relays.