The Siemens 5SM3344-6KK03 is a SENTRON 5SM3-series residual current circuit breaker (RCCB) — a 4-pole, 40 A rated, 30 mA trip device, Type A (pulsating DC and AC fault currents), instantaneous trip, with a 10 kA short-circuit current rating at 400 V AC. Type A detection means it catches both sinusoidal AC faults and pulsating DC faults up to 30 mA — the standard for circuits feeding single-phase electronics, switched-mode power supplies, or variable-speed drives where DC ripple can blind a basic AC-only RCCB.
IP20 rated once installed with conductors connected — typical for enclosed panel use, not washdown.
Rated 40 A continuous at 40 °C and 45 °C ambient; derates linearly to 32 A at 70 °C.