The Siemens 5SM3626-4 is a 2-pole SENTRON residual current circuit breaker (RCCB) rated 63 A at 230 V AC, with a 300 mA Type B trip characteristic and short-time delay. Type B means it detects AC, pulsating DC, and smooth DC fault currents — needed on drives, UPS feeds, or PV inverters where pure sine-wave RCDs would be blind to DC leakage. The 300 mA threshold and intentional delay make it a selective (S-type) device, so it coordinates with downstream 30 mA RCCBs: a ground fault on a branch trips the branch first, not this main isolator.
Snaps onto DIN rail (REG mounting) and occupies 4 width units (72 mm wide). Terminal capacity accepts 1.5 to 25 mm² solid or stranded copper — covers everything from a 2.5 mm² lighting circuit up to a 16 mm² feeder. Tightening torque is 2.5 to 3 N·m, typical for SENTRON screw terminals; no special tooling needed. Supply can land top or bottom; the SIGRES function (residual current detection even when switched off) works with bottom feed.