The Siemens 5SM3314-0 is a SENTRON RCCB (residual current circuit breaker) — a 2-pole, Type AC instantaneous device rated for 40 A at 40 °C with a 30 mA tripping fault current. It mounts on DIN rail (REG) and is designed for 230 V AC supply at 50 Hz.
Rated current is 40 A at 40 °C and 45 °C, derating to 38.4 A at 50 °C, 36.8 A at 55 °C, 35.2 A at 60 °C, 33.6 A at 65 °C, and 32 A at 70 °C. This derating curve matters when the RCCB is installed in a crowded enclosure with elevated ambient — the 40 A rating is only valid up to 45 °C; above that, you must account for the reduced capacity to avoid nuisance tripping from thermal overload. Short-circuit current rating (SCCR) is 10 kA per IEC 61008-1, with a lower 0.5 kA rating per EN 60898. Let-through energy (I²t) is rated at 70 000 A²·s, and the permissible let-through current is 7 500 kA — these values are used for selectivity coordination with upstream overcurrent devices. The RCCB is not a short-circuit protective device; it relies on the upstream MCB or fuse to clear faults, and these figures tell the designer whether the coordination holds. It is intended for indoor, dry-location use inside a panel.
Fastens onto DIN rail (REG) per. Depth is 70 mm, height 90 mm. Mounting position is any orientation. Power supply connection can be top or bottom. Silicon-free construction is specified for applications where silicone outgassing could contaminate contacts or optics.