What this reversing starter is and what it does
The Siemens 3RK1300-1KS01-1AA4 is a reversing starter — a compact electromechanical unit that combines two contactors and a motor protection relay in one housing to control the direction of a three-phase motor. It is rated 12 A in AC-3 duty at 400 V, which means it switches standard squirrel-cage motors up to 5.5 kW without derating for the reversing function. The unit includes a bimetal motor protection relay and short-circuit protection via circuit-breakers, so it covers both overload and fault clearing in a single panel-mounted device. The IP65 enclosure means the entire assembly is sealed against dust and low-pressure water jets — suitable for washdown areas or outdoor cabinets where a standard open starter would need a separate enclosure.
Integration and connectivity
Control supply is 24 V DC (20.4 to 28.8 V tolerance), and the unit communicates via PROFIBUS DP over the backplane bus — no PROFINET or AS-Interface onboard. The motor brake output is integrated, saving a separate contactor for brake control on vertical-axis or holding-brake motors. Dimensions are 270 mm high, 140 mm wide, and 134 mm deep. The main power connections use sockets per ISO 23570 for both infeed and load-side outgoing feeder, which standardizes the cabling interface across the Siemens SIRIUS modular system.