The Siemens 3RK1303-6BS71-1AA3 is a reversing starter with solid-state switching contacts, rated 3 A at AC-3 duty on 400 V. It runs on a 24 V DC control supply (20.4 to 28.8 V permissible range). The enclosure carries IP65 protection, so it handles washdown environments in food-and-beverage or automotive lines without a separate cabinet. Communication runs over PROFIBUS DP, not PROFINET — that matters if your backbone is Siemens S7-300/400 with a DP master. Two parameterizable digital inputs on M12 sockets handle limit switches or start commands. No digital outputs onboard; the load switching is handled by the solid-state contactor inside.
Sourcing and lifecycle
RoHS compliance date is marked as May 1, 2012, which covers the substance prohibitions under EU Directive 2011/65/EU.
Mounting and integration
Dimensions are 250 mm high, 130 mm wide, 125 mm deep. The main energy infeed and load-side outgoing feeder use sockets per ISO 23570 — that is the standard hybrid connector interface for Siemens motor starters. Supply voltage transmission and communication transmission also use hybrid sockets/plugs, so the wiring harness is a single multi-conductor cable per drop. Short-circuit protection is via an upstream fuse (not a circuit breaker). The unit has a 100 kA rated short-circuit current at 400 V, meaning it can interrupt faults up to that level without cascading damage upstream — useful for high-fault-capacity panels.
Ratings and what they mean
The AC-3 rating of 3 A at 400 V covers motor starting duty — switching a 3-phase induction motor up to roughly 1.5 kW (2 HP) under normal starting conditions. The solid-state contacts handle the inrush without wear, so the auxiliary contact reliability is rated at less than 1 error per 100 million operating cycles. Full motor protection is built in, with brake control at 400 V AC available. Minimum operating frequency is 1 cycle per hour, so it is not intended for high-speed reversing applications like servo-style indexing.