The Siemens SIRIUS 3RV1421-0DA10-ZI41 is a three-pole circuit breaker designed specifically for transformer protection, rated at 0.32 A continuous current with a CLASS 10 trip characteristic — meaning it allows the inrush of a transformer without nuisance tripping while still clearing a sustained overload within 10 seconds at 7.2× Iₑ. Mounts via screw and snap-on onto 35 mm standard mounting rail per DIN EN 50022, and the 45 mm width (three 15 mm modules) fits standard DIN-rail enclosures — backwards and side clearances are both 0 mm, meaning it can be butted directly against adjacent devices.
Integration & Wiring
Main and auxiliary/control circuits both terminate at screw-type terminals; the main circuit accepts solid or stranded conductors from 1 to 6 mm² (2x per terminal), and AWG 14–10 for the main contacts. Finger-safe touch protection (IP20 on the front) means the terminals are guarded against accidental contact — no extra shrouding needed in a standard panel. The product accepts an auxiliary switch extension (sold separately), though the base unit ships with zero CO contacts for auxiliary contacts.
Environmental & Mechanical
Power dissipation in hot operating state is 5.5 W total (1.8 W per pole), so thermal management in a crowded cabinet is straightforward.