RCCB for universal-current-sensitive protection
The Siemens 5SM3324-4 is a 2-pole SENTRON residual current circuit breaker (RCCB) rated 40 A at 230 V AC, with a 30 mA trip threshold and Type B residual current characteristic. Type B means it detects smooth DC fault currents in addition to AC and pulsed DC — essential for circuits feeding variable-frequency drives, UPS systems, or EV charging equipment where pure AC-sensing RCCBs would miss a DC fault. The short-time delayed design (S-type) provides selectivity: it withstands transient earth-leakage surges up to 3 kA (8/20 µs) without nuisance tripping, coordinating with downstream RCCBs so only the faulted branch clears. Rated short-circuit current withstand is 10 kA per EN 60898 and IEC 61008-1, adequate for most residential and light-commercial distribution boards. The 2-pole form factor (4 modular width units, 72 mm wide) mounts on DIN rail (REG) in any orientation, with top or bottom feed permitted. Mechanical service life is 10 000 operating cycles typical.
DIN-rail integration and panel fit
Snaps onto standard 35 mm DIN rail; the 72 mm width (4 MW) occupies four adjacent 18 mm slots. Depth of 70 mm (installation depth 70 mm) leaves clearance for wiring gutters in a typical 120 mm deep enclosure. IP20 rated with conductors connected — suitable for enclosed distribution boards, not open-panel washdown zones. Ambient range -25 °C to 45 °C operating; storage from -40 °C to 75 °C. The silicon-free construction avoids outgassing issues in sealed cabinets with sensitive electronics.