The Siemens 3RV1421-1GA10-0BA0 is a SIRIUS-brand circuit breaker specifically designed for transformer protection. It carries a rated continuous current of 6.3 A and a CLASS 10 trip characteristic, meaning it will trip within 10 seconds at 7.2× rated current — fast enough to protect a transformer winding from sustained overload but coordinated to ride through inrush. Breaking capacity is 100 kA at 240 V, 400 V, and 500 V AC, dropping to 6 kA at 690 V AC. No ground-fault detection on this variant.
Zero clearance needed above or below (0 mm backwards, 0 mm at the sides), so you can pack it tight against other devices on the rail. Main circuit terminals are screw-type, accepting 2x (1…2.5 mm²) solid or 2x (2.5…6 mm²) stranded. AWG equivalents are 2x (14…10).
Environmental and electrical ratings
Operates from -50 °C to +60 °C ambient, with storage and transport range extending to -50…+80 °C. Shock-rated at 25 g for 11 ms. Power dissipation runs 7.25 W total in hot operating state (2.4 W per pole) — thermal management is straightforward in a standard IP20 enclosure. Mechanical endurance is 500 operations of the main contacts typical. Maximum switching frequency at AC-3 duty is 15 operations per hour.