What this RCCB does and where it fits
The Siemens SENTRON 5SV3344-4 is a 4-pole Type B residual current operated circuit breaker (RCCB) rated 40 A with 30 mA sensitivity on a 400 V AC supply. Type B detection handles AC, pulsating DC, and smooth DC fault currents — the right choice for drives, UPS systems, and PV inverters where Type A won't catch a pure DC fault. Short-time delayed (S-type) design gives it selectivity upstream of downstream RCCBs, so a ground fault on a branch trips the branch device first, not this main protector. Rated short-circuit current withstand is 10 kA per IEC 61008-1. That means it can safely interrupt a bolted fault up to 10 kA without welding contacts or rupturing the case — sized for most commercial and light industrial distribution boards. The 4-pole form factor handles three-phase plus neutral, common for 400 V three-phase main incomers or sub-distribution.
Mounting and panel fit
Snaps onto standard DIN rail (REG), occupies 4 modular width units (72 mm wide). Depth is 70 mm, matching the standard SENTRON RCCB/MCB footprint — no extra clearance needed behind the DIN rail. Mounting position is unrestricted, so it can go sideways or upside-down in a tight gland plate layout without derating. IP20 with conductors connected; keep it inside a distribution board or enclosed panel. Supply can enter from top or bottom. The SIGRES function (switched-off state power supply) works from either direction, which simplifies busbar routing in a multi-row panel. Silicon-free construction avoids outgassing issues around sensitive contacts or electronics.