What it is and what it does
The Siemens SIMATIC 3RK1308-0AE00-0CP0 is a direct-on-line motor starter designed for switching and protecting three-phase motors up to 12 A at 40 °C ambient. It integrates a contactor and overload relay in one 30 mm wide housing that plugs onto a base unit for DIN-rail mounting, saving panel space compared to discrete components. Rated for continuous operation with an MTBF of 46 a, this starter is suited for conveyor, pump, and fan applications where the motor starts directly across the line. The adjustable trip class — selectable OFF, 5, or 10 — lets you match the thermal protection to the motor's starting characteristic: class 10 covers standard squirrel-cage motors, class 5 tightens protection for high-efficiency types with faster start times.
Communication and control
Both PROFINET and PROFIBUS DP protocols are built in, eliminating the need for a separate gateway or communication module. The starter accepts 4 bytes of input data and returns 2 bytes of output data, mapping status and control words into the PLC's I/O image. On-delay of 20 ms and off-delay of 35 to 50 ms are fixed, so sequence timing must account for these windows. Supply voltage range is 20.4 to 28.8 V DC, typical for a 24 V control loop. The safe state is load circuit open — on loss of communication or a fault, the output drops out, leaving the motor unpowered. This aligns with fail-safe behavior expected in a standard (non-SIL) motor starter.
Installation and environment
Mounts vertically or horizontally on a DIN rail via the pluggable base unit; derating applies for horizontal orientation — consult the manual. The 30 × 142 × 150 mm footprint (width × height × depth) fits standard 30 mm slot spacing. Clearance of 50 mm above and below is required for airflow and wiring access. Operating temperature range is -25 to +60 °C with derating above 40 °C, storage and transport range -40 to +70 °C. Pollution degree 2 and overvoltage category III suit industrial control panels with fixed wiring. Vibration resistance is 15 mm at 6 Hz / 2g up to 500 Hz; shock resistance 6g for 11 ms — adequate for most machine-mounted enclosures.