Transformer-protection circuit breaker, 1.6 A, 100 kA
The Siemens SIRIUS 3RV1421-1AA10-ZX95 is a 3-pole circuit breaker designed specifically for transformer protection, rated at 1.6 A continuous current with a 100 kA breaking capacity across 240 V, 400 V, 500 V, and 690 V AC — meaning it clears faults up to that level without upstream coordination issues. Trip Class 10 gives it a thermal overload response fast enough to protect transformer windings during inrush without nuisance tripping on normal magnetization peaks.
Ratings that matter for the BOM line
Rated operational voltage goes to 690 V AC, with AC-3 switching rated at the same 690 V maximum. Power dissipation runs 7.25 W hot total, 2.4 W per pole — low enough that multiple units side-by-side on the rail stay within a standard enclosure's thermal budget. Screw terminals on both main and auxiliary circuits accept solid or stranded wire: 2x (1 to 2.5 mm²) and 2x (2.5 to 6 mm²), with AWG equivalents 2x (14 to 10).
RoHS compliance date is 01.05.2012; the part carries substance prohibitance documentation for EU markets.
Shock rated at 25 g for 11 ms, which covers typical panel vibration from contactors and drives cycling nearby. Maximum operating frequency in AC-3 duty is 15 operations per hour — not a high-cycling device; for frequent switching look at the contactor paired with this breaker. Surge voltage resistance rated at 6 kV.