What this RCCB does on your panel
The Siemens 5SM1646-6 is a 4-pole residual current circuit breaker (RCCB) from the SENTRON 5SM1 series, rated for 63 A at 400 V AC, 50 Hz. It trips instantaneously on type A fault currents (pulsating DC and sinusoidal AC) at 300 mA residual — the common choice for circuits with single-phase rectifiers, switched-mode supplies, or variable-speed drives that generate smooth DC fault components.
Above that, the thermal curve drops: 60.48 A at 50 °C, 57.96 A at 55 °C, 55.44 A at 60 °C, 52.92 A at 65 °C, and 50.4 A at 70 °C. That SCCR covers most distribution boards fed from a typical 400 V transformer up to about 200 kVA — enough for a production line sub-panel. The I²t let-through is rated 70,000 A²·s, so check coordination with the upstream MCB or fuse. Mechanical life is 10,000 switching cycles typical. That's standard for a distribution RCCB — not a switching contactor, but fine for infrequent manual test or isolation. For high-cycle applications like daily E-stop testing, budget for more frequent replacement.
Snaps onto DIN rail (REG profile), 4 width units (4 x 18 mm). Mounting position is any — no orientation restriction. Installation depth is 55 mm from the rail surface. IP20 with conductors connected, so it's for enclosed distribution boards only — not for washdown or outdoor exposed mounting.