Reversing starter with fieldbus and IP65 enclosure
The 3RK1303-5BS44-3AA0 is a Siemens SIRIUS reversing starter — a compact motor control unit that handles forward/reverse switching in a single enclosure. Its 3 A rating at 400 V AC-3 duty means it's sized for small reversing motor loads like conveyor drives or actuator positioning, not for high-current main drives. The solid-state motor protection covers overload and phase loss, with a mechanical switching contact for the main circuit. Communication is via PROFIBUS DP, not PROFINET, so it integrates into existing DP networks. The 4 digital inputs are parameterizable, giving you flexibility to wire limit switches, pushbuttons, or sensor feedback directly into the starter without a separate I/O block. Supply voltage is 24 V DC nominal (20.4–28.8 V range), which is standard for control circuits.
The unit measures 250 mm high, 130 mm wide, and 107 mm deep. The load-side outgoing feeder and main energy infeed both use sockets per ISO 23570 — a standardized connector interface that speeds wiring and reduces termination errors. The line-side supply voltage connects via a hybrid plug, and communication transmission uses a hybrid socket. This modular connector scheme means you pre-cable the panel harness and simply plug the starter in during commissioning.
Sourcing posture
The combination of IP65, PROFIBUS DP, and 3 A AC-3 rating makes it a specific fit for small reversing motor applications in wet or dusty environments — confirm the 3 A motor rating matches your load before committing the BOM line.