What this reversing starter is and where it fits
The Siemens 3RK1300-1JS01-1AA4 is an electromechanical reversing starter from the SIRIUS EM 300 RS family, designed for the ET 200X distributed I/O system. It combines two contactors with a bimetal overload relay in a single IP65 enclosure, so it handles forward/reverse motor control and overload protection in one package — no separate contactor-and-relay assembly needed. The IP65 rating means the housing and all connections withstand washdown environments, making it suitable for food-and-bev, packaging, or material-handling lines where hose-down cleaning is routine. Rated operating voltage is 400 to 500 V AC, with a motor output of 4 kW in AC-3 duty (squirrel-cage motors) at 400 V. The setting range on the bimetal overload is 7.0 to 10 A, so it covers motors drawing that full-load current — the 7 A minimum and 10 A maximum are the adjustment limits, not the trip thresholds. The short-circuit breaking capacity (Icu) at 400 V is 50 A, meaning the integrated circuit-breaker-style short-circuit protection safely interrupts faults up to that level without cascading upstream. This unit includes a motor brake output rated DC 500 V / 1 A, intended for internally supplied brakes — common on vertical-load conveyors or holding applications where the brake must engage when power is removed. Communication is via PROFIBUS DP, so it integrates into a Siemens S7-300/400 or ET 200X bus network without a separate gateway.
Integration notes — panel and wiring
The enclosure measures 134 mm deep by 140 mm wide by 270 mm high — a compact footprint for a reversing starter with integrated brake output and bus communication. Main current circuit connections use tab terminals (fast-on type), common in distributed I/O boxes where quick wiring and field replacement matter. Operating ambient temperature range is 0 to 55 °C, so it is fine for unventilated enclosures on the plant floor but not for freezer or high-heat zones.