The Siemens 5SM3646-6KK01 is a 4-pole residual current operated circuit breaker (RCCB) from the SENTRON 5SM3 series, rated 63 A at 400 V AC, 50 Hz, with a 300 mA tripping residual current. Type A detection means it catches sinusoidal AC fault currents plus pulsating DC fault currents up to 6 mA smooth DC — the standard for mixed-load panels with single-phase rectifiers, VFDs, or switching power supplies downstream. The short-time delayed design (selective type) allows a 3 kA surge current resistance without nuisance tripping, so it coordinates with downstream MCBs on motor-start or capacitor inrush. Mounts on DIN rail (REG), occupies 4 width units (72 mm), and accepts conductors from 1.5 to 25 mm² solid or stranded at the screw terminals, torqued to 2.5–3 N·m.
Panel integration and wiring constraints
DIN-rail snap-on, any mounting position. Installation depth is 70 mm; the device body is 77 mm deep, so a 100 mm deep enclosure leaves clearance for wiring. Supply feeds from top or bottom — no mandatory orientation. IP20 with connected conductors, meaning the terminals are finger-safe only when wired inside a distribution board. Ambient range -25 to +45 °C; storage -40 to +75 °C. Overvoltage category III, sized per DIN 43880 size 1.