What this RCCB is and what the ratings mean for your panel
The Siemens SENTRON 5SM3626-4KK14 is a 2-pole residual current circuit breaker (RCCB) rated 63 A at 40 °C and 230 V AC, with a B+ fault current type and short-time delayed switching function. The 63 A rating at 40 °C is the continuous current it carries in a panel at that ambient — at 70 °C it still holds 50.4 A, so the thermal derating curve is real and worth checking if your enclosure runs hot near the kiln or furnace line. The B+ type detects AC, pulsating DC, smooth DC, and high-frequency fault currents up to 1 kHz, which covers variable-speed drive leakage and modern power supply earth faults that a standard AC type would miss. The short-time delayed design (S-type) means it withstands transient leakage pulses up to 3 kA surge current without tripping, giving selectivity with downstream instantaneous RCCBs — essential for a distribution board feeding multiple sub-circuits. The 10 kA short-circuit current rating (SCCR) tells you it safely interrupts faults up to that level without welding contacts or cascading upstream. Mounts on DIN rail (REG), 4 width units, 72 mm wide × 90 mm tall × 70 mm deep — fits standard distribution board cutouts. IP20 with conductors connected, finger and back-of-hand safe per the protection class.
Integration and mounting notes
Snaps onto standard 35 mm DIN rail. Mounting position is any orientation. The supply cord can enter from the top or bottom — bottom entry also powers the SIGRES function in the switched-off state. Installation depth is 70 mm, matching the device depth. The 4 width units (72 mm) occupy four 18 mm module spaces in a distribution board. Silicon-free construction, suitable for environments where silicone outgassing could contaminate contacts or optics.
Thermal derating across ambient temperature
Rated current is 63 A at both 40 °C and 45 °C ambient. At 50 °C it derates to 60.5 A, at 55 °C to 58 A, at 60 °C to 55.4 A, at 65 °C to 52.9 A, and at 70 °C to 50.4 A. Operating ambient range is -25 °C to 45 °C; storage range is -40 °C to 75 °C. If the panel sits in a 50 °C control room near the preheater tower, size the upstream protective device for the derated value, not the nameplate 63 A.