What this reversing starter is and where it fits
The Siemens 3RK1300-0JS01-1AA3 is an electromechanical reversing starter from the SIRIUS EM 300 RS family, designed as a drop-in motor management module 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 for washdown environments — no separate panel enclosure required when mounted directly on a machine frame. Rated 0.25 kW in AC-3 duty at 400 V, with a setting range of 0.7 to 1.0 A, this starter handles small three-phase induction motors — typical for conveyor drives, agitators, or pump stations in food-and-bev or material-handling lines where reversing direction is needed and the motor brake must be controlled from the same unit. The operating voltage range is 400 to 500 V AC, and the unit carries a maximum short-circuit breaking capacity of 50 A at 400 V, meaning the integrated circuit-breaker coordination is sized for fault currents up to that level without upstream damage.
PROFIBUS DP and brake integration — what the bus and brake output mean on a real line
Onboard PROFIBUS DP communication (no AS-interface) lets this reversing starter exchange start, stop, direction, and fault status directly with a higher-level controller over the fieldbus — no separate I/O wiring for each motor. The bus connection is integral to the ET 200X backplane; the starter simply snaps onto the bus rail and addresses itself via the rotary switch on the base module. The integrated motor brake output handles internally supplied DC brakes — common on small geared motors where the brake coil is fed from a rectifier inside the motor terminal box. This saves an external brake rectifier and a separate control relay; the starter's brake contact switches the AC supply to the motor's internal brake rectifier, so the brake releases when the motor runs and engages when the contactor drops.
IP65 enclosure — deployment context for washdown and outdoor use
Rated IP65, the enclosure is dust-tight and protected against water jets from any direction. This means the starter can be mounted directly on a machine frame in a food-processing area, a washdown station, or an outdoor conveyor gantry without a separate cabinet. The tab terminals for the main current circuit accept fast-on connectors, keeping field wiring quick and sealed. Ambient operating temperature range is 0 to 55 °C, which covers most industrial floor conditions but not freezer or high-heat zones — if the line runs above 55 °C ambient, the starter needs to be relocated or derated.