The Siemens 3RK1300-0KS01-1AA1 is an electromechanical reversing starter from the SIRIUS series, designed for motor control in distributed automation environments. It integrates a reversing contactor, motor protection via a bimetal overload relay, and a PROFIBUS DP communication interface into a single IP65-rated enclosure — meaning it can be mounted directly on the machine or in a field junction box without a separate control cabinet. The 0.37 kW rating at AC-3 duty (400 V) covers small three-phase motors typical of conveyor drives, valve actuators, or pump stations. The setting range of 0.9 to 1.25 A on the bimetal relay matches the full-load current of a 0.37 kW motor at 400 V, so the overload protection is factory-scaled to the motor size.
The AC-3 rating of 0.37 kW at 400 V is the motor-switching capability under starting and stopping conditions (inrush up to 8× FLC). The operating voltage range of 400 to 500 V AC covers standard European 400 V three-phase networks and 480 V North American systems.
Communication and brake control
PROFIBUS DP onboard allows the starter to be addressed directly from a PLC or DCS, eliminating the need for a separate remote I/O module for start/stop and direction commands. The integrated motor brake output supplies DC 24 V / 3 A for an externally supplied brake — common on vertical-axis drives or holding-brake motors. This means the brake is controlled synchronously with the motor contactor, so the brake releases before the motor starts and engages after it stops, without a separate timing relay.