What it is and what it does
The Siemens 3RK1395-6LS71-3AD5 is a SIRIUS reversing starter — a single enclosure that handles forward and reverse motor control without an external interlock. It's built for a 400 V line, rated 12 A and 5.5 kW at that voltage, and also carries ratings of 5.5 kW at 500 V, 3 hp at 220/230 V, and 7.5 hp at 460/480 V. The 24 V DC control supply powers the onboard logic and I/O.
What the ratings mean for your panel
IP65 means the enclosure is dust-tight and protected against low-pressure water jets — it's suited for washdown areas or outdoor cabinets where a standard IP20 starter would need a separate enclosure. The 148 mm depth and 294 mm width give you the footprint to plan on a sub-panel or machine frame; screw fixing is the mounting method. Trip class is selectable among 5, 10, 15, and 20, so you match the overload protection to the motor's thermal time constant — a 5 for fast-responding short-duty motors, a 20 for high-inertia loads that take longer to start. The 25 ms ON-delay and 35 ms OFF-delay give you programmable timing for reversing without hammering the load. Four digital inputs and two digital outputs are integrated, so you can wire start/stop, direction-select, and feedback directly without a remote I/O block. The main power circuit connects via a HAN Q4/2 plug (ISO 23570), which simplifies field replacement — unplug the old, plug in the new.
Where it lives and how it holds up
Mounting position is flexible — vertical, horizontal, or flat — so it fits tight enclosures or machine-mounted installations. Operating temperature range is -25 to +55 °C; storage and transport range is -40 to +70 °C. It handles 12g shock at 11 ms and 2g vibration at 7 mm amplitude, which covers most conveyor and pump applications without a separate isolation mount.