What it is and where it fits
The Siemens 3RK1300-0DS01-1AA3 is an EM 300 RS electromechanical reversing starter designed for the ET 200X distributed I/O system. It combines a reversing contactor, bimetal overload relay, and PROFIBUS DP communication in a single IP65-rated enclosure — so it lives right on the machine, not in a central panel. Rated at 0.09 kW in AC-3 duty at 400 V, with a setting range of 0.22 to 0.32 A. That means it's sized for small three-phase motors — think conveyor drives, small pumps, or actuator feeds — where you need forward/reverse control and motor protection in one compact, field-mounted package.
Key ratings and what they mean for fit
The IP65 rating means the enclosure is dust-tight and protected against low-pressure water jets — suitable for washdown environments like food processing or packaging lines. No need for an extra cabinet; it mounts directly on the machine frame. The maximum short-circuit breaking capacity (Icu) at 400 V is 50 A. That's the fault current the device can safely interrupt; upstream protection (circuit-breaker or fuse) must be coordinated to keep fault energy below this level. PROFIBUS DP onboard means it talks directly to the PLC without a separate gateway. The 9-pole motor feeder and power connection handle the motor cable and brake wiring through a single connector — reduces field wiring time.
Lifecycle and sourcing reality
The integrated brake contact (product component motor brake output) supports internally supplied DC brakes — common on small holding brakes for vertical-axis motors. Confirm your brake voltage and polarity match the internal supply before wiring.