What it is and where it lands
The Siemens 3RK1300-0CS01-1AA1 is an EM 300 RS electromechanical reversing starter designed for the ET 200X distributed I/O system. It integrates a reversing contactor, bimetal overload relay, and PROFIBUS DP communication into a single IP65-rated enclosure — a self-contained motor control unit for small reversing loads in washdown or dusty environments. Rated at 0.06 kW in AC-3 duty at 400 V, it covers small three-phase motors — pumps, conveyors, or valve actuators — where space and sealing matter more than a panel-mounted contactor pair. The setting range of 0.18 to 0.25 A matches the motor full-load current directly via the bimetal relay.
Key ratings and what they mean for fit
The 0.06 kW AC-3 rating at 400 V defines the maximum three-phase induction motor this starter can switch under normal starting conditions. AC-3 covers starting and plugging of squirrel-cage motors — the dominant duty for reversing starters. The 50 A short-circuit breaking capacity (Icu) at 400 V means the integrated circuit-breaker-style short-circuit protection can safely interrupt a fault up to that level without upstream device damage. Operating voltage spans 400 to 500 V. The 0 to 55 °C ambient range suits most indoor industrial environments. IP65 protection means the enclosure is dust-tight and protected against low-pressure water jets — suitable for food processing lines, washdown zones, or outdoor installation under a canopy. The 9-pole motor feeder and 9-pole power connection are tab terminals, so panel wiring uses standard quick-connect receptacles.
Brake output and PROFIBUS integration
This variant includes a motor brake output rated DC 24 V / 3 A for externally supplied brakes — common on vertical-axis conveyors or hoists where the brake must engage when the motor is de-energized. The brake contact is integrated into the reversing starter, eliminating a separate brake relay. PROFIBUS DP communication is built in, so the starter connects directly to a PROFIBUS DP master without a separate gateway. This is the ET 200X ecosystem's native fieldbus — the starter appears as a distributed I/O device on the bus, with control and status data mapped into the PLC's process image.
Physical footprint and panel integration
The enclosure measures 140 mm wide by 270 mm high by 134 mm deep — a compact footprint for a reversing starter with integrated brake output and PROFIBUS. It mounts directly to the ET 200X backplane or to a mounting plate via the enclosure's fixing points. The IP65 housing means it can be mounted on the machine frame or in a field enclosure, not just inside a central control panel.