What it is and what it does
The Siemens SIRIUS 3RK1395-6LS41-0AD3 is a direct motor starter in a self-contained IP65-rated enclosure, designed for distributed motor control where the starter lives at the load rather than in a central panel. Its 12 A rating at 400 V AC (AC-3 duty) covers motors up to 5.5 kW at 400 V, 7.5 hp at 460/480 V, or 10 hp at 575/600 V — so it handles the common 3-phase induction motor sizes you see on pumps, conveyors, and small fans. The Trip Class is field-selectable among 5, 10, 15, and 20, which means you tune the overload protection to the motor's starting characteristic: a hard-starting compressor gets Class 20, a low-inertia fan gets Class 10. That flexibility saves stocking multiple variants.
Where it lives and how it connects
This starter is built for washdown or dusty environments — the IP65 rating means the enclosure seals against hose-directed water and airborne dust, so it mounts directly on the machine frame or a bracket near the motor, not back in a climate-controlled cabinet. The main power circuit connects via a HAN Q4/2 plug per ISO 23570, a standard industrial connector that makes swap-out fast: unplug the old starter, plug in the replacement, torque the four screws. Screw fixing to the mounting surface, and you can orient it vertically, horizontally, or flat — no derating for sideways mounting. Dimensions are 215 mm high, 294 mm wide, 148 mm deep.
Control and I/O
The starter carries 4 digital inputs and 2 digital outputs, enough for local start/stop, feedback from the motor, and a run-status signal back to the PLC. It runs on a 24 V DC control supply (20.4 to 28.8 V range), which is standard for modern automation. On-delay is 85 ms, off-delay 65 ms — fast enough for sequencing but not so fast that it false-triggers on contact bounce. No PROFINET or PROFIBUS onboard; this is a hardwired I/O block, not a fieldbus node.
Environmental tolerance
Rated for operation from -25 to +55 °C, storage and transport from -40 to +70 °C. Shock resistance is 12g for 11 ms; vibration resistance is 7 mm at 2g. That covers the mechanical stress on a machine-mounted starter from normal production line vibration and occasional bumps.