What it is and what it does
The Siemens 3RK1300-0FS01-0AA4 is an EM 300 DS electromechanical direct starter designed for the ET 200X distributed I/O system. It is a motor protection and switching device that integrates a bimetal overload relay, a contactor, and a PROFIBUS DP communication interface into a single IP65-rated enclosure. The setting range is 0.35 to 0.5 A, matched to a motor rated 0.12 kW at 400 V in AC-3 duty (cage-induction motor switching). The operating voltage range is 400 to 500 V.
Key ratings and what they mean for fit
The AC-3 rating of 0.12 kW at 400 V is the motor-switching capacity — this part is sized for small three-phase motors up to that power. The 0.35 to 0.5 A setting range must match the motor full-load current; if your motor draws outside that window, this starter won't protect it. The maximum short-circuit breaking capacity (Icu) at 400 V is 50 A, meaning the device can safely interrupt a fault current up to that level without upstream protection taking over. For higher fault currents, a circuit breaker or fuse upstream must coordinate. IP65 means the enclosure is dust-tight and protected against low-pressure water jets — suitable for washdown areas in food, beverage, or light industrial environments. The part is not submersible. PROFIBUS DP protocol is built in, so the starter communicates directly on a PROFIBUS DP network without an extra gateway. No AS-interface support on this variant.
Where it is used
The integrated motor brake output (DC 500 V/1 A) allows direct control of an internally supplied brake — common on vertical-load axes or holding-brake motors.
Sourcing and lifecycle
Because this is a current-production Siemens part, it is sourced to order against an RFQ. No surplus or broker channel is needed.
Integration notes
Mounts in an ET 200X station; the 140 mm width, 270 mm height, and 134 mm depth determine the panel cutout and enclosure size. Tab terminals on the main current circuit accept standard fork or ring lugs. The 9-pole motor feeder and 9-pole power connection are pre-wired via the ET 200X backplane — no field wiring of the power bus is required.