What it is and what it does
The Siemens 3RK1395-6LS71-0AD3 is a SIRIUS direct motor starter in a fully enclosed IP65 housing — no need to box it separately for washdown or dusty environments. It's rated for 5.5 kW at 400 V AC (12 A) and covers motor protection with selectable trip classes 5, 10, 15, and 20, so you can match the thermal curve to the load: fast for submersible pumps, slower for high-inertia fans. Power connection uses a HAN Q4/2 plug according to ISO 23570 — a standard industrial connector that mates quickly and keeps the enclosure seal intact. The unit also carries 4 digital inputs and 2 digital outputs, enough for local start/stop and a feedback signal back to the PLC without an extra I/O block.
Where it fits and how it mounts
This starter measures 294 mm wide by 215 mm high by 148 mm deep — a compact footprint for a fully self-contained motor starter. It mounts via screw fixing and can be installed vertically, horizontally, or flat, which helps when you're squeezing it into a tight corner of a machine frame or a wall-mounted enclosure. The IP65 rating means it's sealed against dust ingress and low-pressure water jets — suitable for standalone mounting on a conveyor line or near washdown stations without a secondary cabinet. Vibration resistance is spec'd at 7 mm / 2g and shock at 12g / 11 ms, so it holds up on vibrating machinery like compressors or sorting shakers.
What the ratings mean for your panel
The 12 A rating at 400 V AC is the continuous motor current under AC-3 duty (starting/running squirrel-cage motors). The selectable trip class lets you dial in the overload protection without swapping heater packs — a single part covers a range of motor FLCs. Off-delay is 35 ms and on-delay is 25 ms, which is fast enough for most sequencing but not so fast that nuisance trips from brief supply dips become a problem. Supply voltage is 24 V DC nominal (20.4 to 28.8 V range), so it runs off a standard control transformer or industrial power supply. The digital inputs are 24 V DC as well, keeping the control wiring consistent across the panel.