The Siemens SENTRON 5SM3444-6LA01 is a 4-pole residual current circuit breaker (RCCB) rated for 40 A at 400 V AC, 50 Hz, with a 100 mA trip threshold and type A fault current sensitivity. The type A designation means it detects both sinusoidal AC residual currents and pulsating DC residual currents — needed on circuits feeding single-phase rectifiers, switching power supplies, or variable-speed drives. The 4-pole construction (switching all three phases plus neutral) suits three-phase four-wire systems, common in European industrial and commercial panels. The 40 A rating and 100 mA trip target sub-distribution boards feeding mixed loads — motor circuits, lighting, socket outlets — where a 30 mA device would nuisance-trip on normal cable leakage. The short-time delay (also called selective or S-type) allows downstream 30 mA RCCBs to clear first, keeping this unit as the backup; that selectivity is what makes it a panel-main or feeder RCCB rather than a final-circuit device. Mounts on DIN rail (REG profile), occupying 4 width units (about 72 mm). Terminals accept solid or stranded conductors from 1.5 mm² up to 25 mm², with a tightening torque of 2.5 to 3 N·m — the 25 mm² upper end is generous for a 40 A device, allowing easy busbar or larger feeder connections. The part includes thermal overload protection (bimetallic strip) — unusual for an RCCB, which typically only detects residual current. This means the 5SM3444-6LA01 also protects against sustained overcurrent, combining RCD and overload functions in one device. That saves a DIN slot versus a separate RCCB + MCB combination, though it does not provide short-circuit protection (the 10 kA SCCR is its withstand, not its interruption capability for overloads — the thermal element handles that).
The 5SM3 series is the delayed-trip RCCB line within SENTRON, distinct from the instantaneous 5SM1 series. The 5SM3444-6LA01 sits alongside the 5SY4 series MCBs in the same DIN-rail panel ecosystem — they share the same mounting, terminal range, and width-unit grid, so coordination in a distribution board is straightforward.
Deployment context — where this RCCB goes
This RCCB is designed for DIN-rail distribution boards in commercial buildings, industrial control panels, and infrastructure installations. The IP20 rating (with conductors connected and distribution board installed) means it lives inside a closed enclosure — not exposed to washdown or outdoor conditions. The finger and back-of-hand safe protection (per DIN VDE 0106 part 100) means the terminals are touch-safe when the device is mounted in a distribution board — a safety requirement for panel builders in Europe.