The Siemens SENTRON 5SM3346-6KK12 is a 4-pole residual current circuit breaker (RCCB) rated 63 A at 400 V AC — the current-carrying capacity for a 4-wire (3L+N) supply in a standard 50 Hz distribution board. The instantaneous design (no intentional delay) trips within milliseconds of a fault, so it protects personnel but requires selectivity coordination with downstream MCBs to avoid nuisance tripping on branch faults.
Temperature derating — the real-world current limit
Above that, the continuous current must be reduced: 60.48 A at 50 °C, 57.96 A at 55 °C, 55.44 A at 60 °C, 52.92 A at 65 °C, and 50.4 A at 70 °C. If the panel internal temperature runs hot — common in sealed enclosures or near transformers — the effective capacity drops by roughly 20 % at the top end. The I²t value of 70 000 A²·s gives the energy let-through for coordination studies with upstream breakers.
Snap-on DIN rail (REG) mounting, 4 width units (72 mm wide), 77 mm depth, 90 mm height. Installation depth is 70 mm. The bottom-entry power supply cord is standard for RCCBs in this form factor. IP20 with the distribution board installed and conductors connected; finger and back-of-hand safe protection against electrical shock. Silicon-free construction suits applications where outgassing must be avoided, such as in clean rooms or sealed electronics enclosures.