The Siemens 5SM3346-6LA is a 4-pole SENTRON residual current circuit breaker (RCCB) rated for 63 A at 400 V AC, with a 30 mA Type A fault-current trip and built-in thermal overload protection. It's an instantaneous design — no intentional short-time delay — so it clears ground faults the moment they exceed the 30 mA threshold. The Type A designation means it catches both sinusoidal AC fault currents and pulsed DC fault currents up to 1 kHz, which covers most modern electronics and variable-speed drives that generate smooth DC ripple.
The 63 A continuous rating at 400 V AC three-phase means this RCCB handles the full load of a typical sub-distribution board feeding lighting, socket outlets, and general power circuits. The 30 mA residual trip provides shock protection per IEC 60364 — it'll clear a fault before heart fibrillation becomes a risk. The 0 kA short-circuit current rating is critical: this device is NOT rated to interrupt high fault currents on its own. In practice, you install it downstream of a suitably rated MCB or as part of an RCBO assembly.
Tighten to 2.5 to 3 N·m. Ambient range is -25 to +45 °C operating, -40 to +75 °C storage, which covers most indoor electrical rooms and conditioned enclosures.