What this reversing starter packs
The Siemens 3RK1300-0KS01-1AA3 is a SIRIUS EM 300 RS electromechanical reversing starter designed for the ET 200X distributed I/O system — it combines two contactors, a bimetal overload relay, and a motor brake output in a single IP65 enclosure. Rated 0.37 kW at AC-3 duty on a 400 V supply, it covers the small-motor end of the line: pumps, conveyors, and valve actuators that need forward/reverse control without a separate reversing contactor pair. The setting range of 0.9 to 1.25 A (full-scale value 1.25 A) means the bimetal overload matches motors drawing between those FLA values — common for 0.37 kW four-pole motors at 400 V. The 50 A short-circuit breaking capacity at 400 V (Icu) tells you it coordinates with upstream protection up to that fault level without welding the contacts. IP65 lets this live on the machine frame or in a washdown zone — no separate panel needed. The 9-pole motor feeder and 9-pole power connection (tab terminals for the main circuit) handle the reversing wiring internally; you land one motor cable and one supply cable.
PROFIBUS DP and brake output — what they mean on the line
Built-in PROFIBUS DP communication (yes, the protocol is confirmed) lets this reversing starter take start/stop and direction commands directly from the fieldbus — no separate I/O block needed for the motor branch. The integrated motor brake output (24 V DC type per the voltage class) powers an external holding brake, so a vertical-load conveyor or gantry axis gets its brake released when the motor runs and set when it stops, all from the same unit. The operating voltage range of 400 to 500 V AC covers 400 V and 480 V line supplies common in European and North American industrial plants. Ambient temperature range of 0 to 55 °C is standard for indoor machine-mount; derate if the enclosure traps heat above that.
Lifecycle and sourcing reality
For a BOM freeze or a line-down replacement, the 3RK1300-0KS01-1AA3 is specified into the ET 200X system. It is sourced and quoted to order against an RFQ through independent distribution; availability and current pricing are confirmed at quote time.