The Siemens SIMATIC 3RK1304-5LS40-2AA0 is a direct motor starter — a fully enclosed unit that combines a contactor, overload relay, and short-circuit protection into one IP65-rated housing. Out here in the grease, that's the kind of protection that keeps a motor from cooking itself on a seized pump. The unit runs on 24 V DC control voltage, with a permissible range of 20.4 to 28.8 V. It includes four digital inputs via M12 sockets and communicates over both PROFINET and PROFIBUS DP, so it slots into a SIMATIC automation network without extra gateways.
Mounting dimensions are 230 mm high, 110 mm wide, and 150 mm deep. It fastens with screws and can be mounted vertically or horizontally. The main power infeed uses a socket per ISO 23570, so plan for that connector when laying out the panel. At 12 A continuous motor current, this starter covers a 5.5 kW motor at 400 V (rough rule of thumb) — if your motor draws more, step up to the next frame. That's important for coordination with the feeder breaker — if your available fault current is lower, you still get the full rating.