Transformer-Protection Circuit Breaker, 6.3 A, Class 10
The Siemens SIRIUS 3RV1421-1GA15 is a circuit breaker designed specifically for transformer protection, rated at 6.3 A continuous current and Trip Class 10 — meaning it trips within 10 seconds at 7.2× rated current, matching the inrush profile of small to medium transformers. Breaking capacity reaches 100 kA at 240 V, 400 V, and 500 V AC, dropping to 6 kA at 690 V AC — so on a 400 V line it handles worst-case fault currents without cascading upstream, but at 690 V the fault-current ceiling is lower and coordination with upstream devices needs checking.
Main and auxiliary/control circuits use screw-type terminals. Solid wire accepts 2× (0.5…1.5 mm²) and 2× (0.75…2.5 mm²); stranded accepts 2× (1…2.5 mm²) and 2× (2.5…6 mm²). AWG for main contacts is 2× (14…10). Auxiliary switch is transverse design and the product extension supports an auxiliary switch — so you can add a signal contact for remote status without replacing the breaker.