What it is and what it does
The Siemens 3RK1300-0CS01-1AA4 is an EM 300 RS electromechanical reversing starter designed for the ET 200X distributed I/O system. It integrates a bimetal motor protection relay, reversing contactor pair, and PROFIBUS DP communication into a single IP65 enclosure — a self-contained motor control unit for a reversing drive in a washdown zone. Rated at 0.06 kW at AC-3 duty on a 400 V supply, it handles the reversing of small three-phase motors — conveyors, diverters, or gate actuators — up to that load. The setting range of 0.18 to 0.25 A matches the full-load current of the motor, and the bimetal overload provides Class 10 trip protection. The IP65 rating means the housing and all connections are sealed against dust ingress and low-pressure water jets — it mounts directly on the machine frame or in a field junction box, not inside a control cabinet. The tab terminals for the main circuit accept standard fast-on connectors, keeping field wiring quick.
Key ratings and what they mean for fit
The maximum short-circuit breaking capacity (Icu) at 400 V is 50 A. That means the starter can safely interrupt a fault current up to 50 A without welding its contacts — but upstream protection (a circuit breaker or fuse) must limit the prospective fault current to this level. The design assumes circuit-breaker backup per the product spec. Operating voltage is 400 to 500 V AC. Coil voltage type is DC.
Integration and deployment context
This reversing starter is a module in the Siemens ET 200X family — it connects to the system via a 9-pole motor feeder and a 9-pole power connection, and communicates over PROFIBUS DP. The brake contact output (DC 500 V / 1 A) is intended for internally supplied DC brakes on the motor, common in holding-brake applications for vertical axes. Dimensions are 140 mm wide, 270 mm high, and 134 mm deep — it occupies a footprint similar to a small contactor but with the added depth of the bus interface and enclosure. The IP65 housing allows direct mounting on the machine, but the tab terminals and bus connector must be accessible for wiring and service. Ambient temperature range during operation is 0 to 55 °C — adequate for most indoor industrial environments but not for freezer or high-heat zones without derating.
Sourcing and lifecycle
For a BOM freeze or a critical spare, confirm the setting range matches the motor FLA before committing the line. The narrow 0.18 to 0.25 A band means a motor with a slightly higher FLA requires a different starter variant.